Changeset 78da4ab

Timestamp:

Feb 19, 2021, 1:47:09 PM (3 years ago)

Author:

Thierry Delisle <tdelisle@…>

Branches:

ADT, arm-eh, ast-experimental, enum, forall-pointer-decay, jacob/cs343-translation, master, new-ast-unique-expr, pthread-emulation, qualifiedEnum

Children:

4f762d3

Parents:

b44959f

Message:

New implementation of io based on instance burrowing.
Trying to avoid the unbounded growth of the previous flat combining approach.

Location:

libcfa/src/concurrency

Files:

• io.cfa (modified) (14 diffs)
• io/call.cfa.in (modified) (8 diffs)
• io/setup.cfa (modified) (14 diffs)
• io/types.hfa (modified) (6 diffs)
• iofwd.hfa (modified) (3 diffs)
• kernel.hfa (modified) (4 diffs)
• kernel/startup.cfa (modified) (7 diffs)
• kernel_private.hfa (modified) (1 diff)

libcfa/src/concurrency/io.cfa

@@ -17 +17 @@
 
 #if defined(__CFA_DEBUG__)
-        // #define __CFA_DEBUG_PRINT_IO__
-        // #define __CFA_DEBUG_PRINT_IO_CORE__
+        #define __CFA_DEBUG_PRINT_IO__
+        #define __CFA_DEBUG_PRINT_IO_CORE__
 #endif
 
@@ -79 +79 @@
         };
 
-        // returns true of acquired as leader or second leader
-        static inline bool try_lock( __leaderlock_t & this ) {
-                const uintptr_t thrd = 1z | (uintptr_t)active_thread();
-                bool block;
-                disable_interrupts();
-                for() {
-                        struct $thread * expected = this.value;
-                        if( 1p != expected && 0p != expected ) {
-                                /* paranoid */ verify( thrd != (uintptr_t)expected ); // We better not already be the next leader
-                                enable_interrupts( __cfaabi_dbg_ctx );
-                                return false;
-                        }
-                        struct $thread * desired;
-                        if( 0p == expected ) {
-                                // If the lock isn't locked acquire it, no need to block
-                                desired = 1p;
-                                block = false;
-                        }
-                        else {
-                                // If the lock is already locked try becomming the next leader
-                                desired = (struct $thread *)thrd;
-                                block = true;
-                        }
-                        if( __atomic_compare_exchange_n(&this.value, &expected, desired, false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST) ) break;
-                }
-                if( block ) {
-                        enable_interrupts( __cfaabi_dbg_ctx );
-                        park();
-                        disable_interrupts();
-                }
-                return true;
-        }
-
-        static inline bool next( __leaderlock_t & this ) {
-                /* paranoid */ verify( ! __preemption_enabled() );
-                struct $thread * nextt;
-                for() {
-                        struct $thread * expected = this.value;
-                        /* paranoid */ verify( (1 & (uintptr_t)expected) == 1 ); // The lock better be locked
-
-                        struct $thread * desired;
-                        if( 1p == expected ) {
-                                // No next leader, just unlock
-                                desired = 0p;
-                                nextt   = 0p;
-                        }
-                        else {
-                                // There is a next leader, remove but keep locked
-                                desired = 1p;
-                                nextt   = (struct $thread *)(~1z & (uintptr_t)expected);
-                        }
-                        if( __atomic_compare_exchange_n(&this.value, &expected, desired, false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST) ) break;
-                }
-
-                if(nextt) {
-                        unpark( nextt );
-                        enable_interrupts( __cfaabi_dbg_ctx );
-                        return true;
-                }
-                enable_interrupts( __cfaabi_dbg_ctx );
-                return false;
-        }
-
 //=============================================================================================
 // I/O Syscall
 //=============================================================================================
-        static int __io_uring_enter( struct __io_data & ring, unsigned to_submit, bool get ) {
+        static int __io_uring_enter( struct $io_context & ctx, unsigned to_submit, bool get ) {
                 bool need_sys_to_submit = false;
                 bool need_sys_to_complete = false;
@@ -152 +89 @@
                 TO_SUBMIT:
                 if( to_submit > 0 ) {
-                        if( !(ring.ring_flags & IORING_SETUP_SQPOLL) ) {
+                        if( !(ctx.ring_flags & IORING_SETUP_SQPOLL) ) {
                                 need_sys_to_submit = true;
                                 break TO_SUBMIT;
                         }
-                        if( (*ring.submit_q.flags) & IORING_SQ_NEED_WAKEUP ) {
+                        if( (*ctx.sq.flags) & IORING_SQ_NEED_WAKEUP ) {
                                 need_sys_to_submit = true;
                                 flags |= IORING_ENTER_SQ_WAKEUP;
@@ -162 +99 @@
                 }
 
-                if( get && !(ring.ring_flags & IORING_SETUP_SQPOLL) ) {
+                if( get && !(ctx.ring_flags & IORING_SETUP_SQPOLL) ) {
                         flags |= IORING_ENTER_GETEVENTS;
-                        if( (ring.ring_flags & IORING_SETUP_IOPOLL) ) {
+                        if( (ctx.ring_flags & IORING_SETUP_IOPOLL) ) {
                                 need_sys_to_complete = true;
                         }
@@ -171 +108 @@
                 int ret = 0;
                 if( need_sys_to_submit || need_sys_to_complete ) {
-                        __cfadbg_print_safe(io_core, "Kernel I/O : IO_URING enter %d %u %u\n", ring.fd, to_submit, flags);
-                        ret = syscall( __NR_io_uring_enter, ring.fd, to_submit, 0, flags, (sigset_t *)0p, _NSIG / 8);
-                        __cfadbg_print_safe(io_core, "Kernel I/O : IO_URING %d returned %d\n", ring.fd, ret);
-
-                        if( ret < 0 ) {
-                                switch((int)errno) {
-                                case EAGAIN:
-                                case EINTR:
-                                case EBUSY:
-                                        ret = -1;
-                                        break;
-                                default:
-                                        abort( "KERNEL ERROR: IO_URING SYSCALL - (%d) %s\n", (int)errno, strerror(errno) );
-                                }
-                        }
+                        __cfadbg_print_safe(io_core, "Kernel I/O : IO_URING enter %d %u %u\n", ctx.fd, to_submit, flags);
+                        ret = syscall( __NR_io_uring_enter, ctx.fd, to_submit, 0, flags, (sigset_t *)0p, _NSIG / 8);
+                        __cfadbg_print_safe(io_core, "Kernel I/O : IO_URING %d returned %d\n", ctx.fd, ret);
                 }
 
@@ -196 +121 @@
 // I/O Polling
 //=============================================================================================
-        static unsigned __collect_submitions( struct __io_data & ring );
-        static __u32 __release_consumed_submission( struct __io_data & ring );
-        static inline void __clean( volatile struct io_uring_sqe * sqe );
-
-        // Process a single completion message from the io_uring
-        // This is NOT thread-safe
-        static inline void process( volatile struct io_uring_cqe & cqe ) {
-                struct io_future_t * future = (struct io_future_t *)(uintptr_t)cqe.user_data;
-                __cfadbg_print_safe( io, "Kernel I/O : Syscall completed : cqe %p, result %d for %p\n", &cqe, cqe.res, future );
-
-                fulfil( *future, cqe.res );
-        }
-
-        static [int, bool] __drain_io( & struct __io_data ring ) {
-                /* paranoid */ verify( ! __preemption_enabled() );
-
-                unsigned to_submit = 0;
-                if( ring.poller_submits ) {
-                        // If the poller thread also submits, then we need to aggregate the submissions which are ready
-                        to_submit = __collect_submitions( ring );
-                }
-
-                int ret = __io_uring_enter(ring, to_submit, true);
+        static inline unsigned __flush( struct $io_context & );
+        static inline __u32 __release_sqes( struct $io_context & );
+
+        static [int, bool] __drain_io( & struct  $io_context ctx ) {
+                unsigned to_submit = __flush( ctx );
+                int ret = __io_uring_enter( ctx, to_submit, true );
                 if( ret < 0 ) {
-                        return [0, true];
+                        switch((int)errno) {
+                        case EAGAIN:
+                        case EINTR:
+                        case EBUSY:
+                                return [0, true];
+                                break;
+                        default:
+                                abort( "KERNEL ERROR: IO_URING SYSCALL - (%d) %s\n", (int)errno, strerror(errno) );
+                        }
                 }
 
                 // update statistics
                 if (to_submit > 0) {
-                        __STATS__( true,
+                        __STATS__( false,
                                 if( to_submit > 0 ) {
                                         io.submit_q.submit_avg.rdy += to_submit;
@@ -232 +148 @@
                                 }
                         )
-                }
-
-                __atomic_thread_fence( __ATOMIC_SEQ_CST );
+                        /* paranoid */ verify( ctx.sq.to_submit <= *ctx.sq.num );
+
+                        /* paranoid */ verify( ctx.sq.to_submit >= ret );
+                        ctx.sq.to_submit -= ret;
+
+                        /* paranoid */ verify( ctx.sq.to_submit <= *ctx.sq.num );
+
+                        if(ret) {
+                                __cfadbg_print_safe(io, "Kernel I/O : %u submitted to io_uring\n", ret);
+                        }
+                }
 
                 // Release the consumed SQEs
-                __release_consumed_submission( ring );
+                __release_sqes( ctx );
 
                 // Drain the queue
-                unsigned head = *ring.completion_q.head;
-                unsigned tail = *ring.completion_q.tail;
-                const __u32 mask = *ring.completion_q.mask;
+                unsigned head = *ctx.cq.head;
+                unsigned tail = *ctx.cq.tail;
+                const __u32 mask = *ctx.cq.mask;
 
                 // Nothing was new return 0
@@ -253 +177 @@
                 for(i; count) {
                         unsigned idx = (head + i) & mask;
-                        volatile struct io_uring_cqe & cqe = ring.completion_q.cqes[idx];
+                        volatile struct io_uring_cqe & cqe = ctx.cq.cqes[idx];
 
                         /* paranoid */ verify(&cqe);
 
-                        process( cqe );
+                        struct io_future_t * future = (struct io_future_t *)(uintptr_t)cqe.user_data;
+                        __cfadbg_print_safe( io, "Kernel I/O : Syscall completed : cqe %p, result %d for %p\n", &cqe, cqe.res, future );
+
+                        fulfil( *future, cqe.res );
+                }
+
+                if(count) {
+                        __cfadbg_print_safe(io, "Kernel I/O : %u completed\n", count);
                 }
 
                 // Mark to the kernel that the cqe has been seen
                 // Ensure that the kernel only sees the new value of the head index after the CQEs have been read.
-                __atomic_fetch_add( ring.completion_q.head, count, __ATOMIC_SEQ_CST );
+                __atomic_store_n( ctx.cq.head, head + count, __ATOMIC_SEQ_CST );
 
                 return [count, count > 0 || to_submit > 0];
         }
 
-        void main( $io_ctx_thread & this ) {
-                __ioctx_register( this );
-
-                __cfadbg_print_safe(io_core, "Kernel I/O : IO poller %d (%p) ready\n", this.ring->fd, &this);
+        void main( $io_context & this ) {
+                __cfadbg_print_safe(io_core, "Kernel I/O : IO poller %d (%p) ready\n", this.fd, &this);
 
                 const int reset_cnt = 5;
@@ -276 +205 @@
                 // Then loop until we need to start
                 LOOP:
-                while(!__atomic_load_n(&this.done, __ATOMIC_SEQ_CST)) {
+                while() {
+                        waitfor( ^?{} : this) {
+                                break LOOP;
+                        }
+                        or else {}
+
                         // Drain the io
                         int count;
                         bool again;
-                        disable_interrupts();
-                                [count, again] = __drain_io( *this.ring );
-
-                                if(!again) reset--;
-
-                                // Update statistics
-                                __STATS__( true,
-                                        io.complete_q.completed_avg.val += count;
-                                        io.complete_q.completed_avg.cnt += 1;
-                                )
-                        enable_interrupts( __cfaabi_dbg_ctx );
+                        [count, again] = __drain_io( this );
+
+                        if(!again) reset--;
+
+                        // Update statistics
+                        __STATS__( false,
+                                io.complete_q.completed_avg.val += count;
+                                io.complete_q.completed_avg.cnt += 1;
+                        )
 
                         // If we got something, just yield and check again
@@ -308 +240 @@
                         }
 
-                                __STATS__( false,
-                                        io.complete_q.blocks += 1;
-                                )
-                                __cfadbg_print_safe(io_core, "Kernel I/O : Parking io poller %d (%p)\n", this.ring->fd, &this);
-
-                                // block this thread
-                                wait( this.sem );
+                        __STATS__( false,
+                                io.complete_q.blocks += 1;
+                        )
+                        __cfadbg_print_safe(io_core, "Kernel I/O : Parking io poller %d (%p)\n", this.fd, &this);
+
+                        // block this thread
+                        wait( this.sem );
 
                         // restore counter
@@ -320 +252 @@
                 }
 
-                __cfadbg_print_safe(io_core, "Kernel I/O : Fast poller %d (%p) stopping\n", this.ring->fd, &this);
-
-                __ioctx_unregister( this );
+                __cfadbg_print_safe(io_core, "Kernel I/O : Fast poller %d (%p) stopping\n", this.fd, &this);
         }
 
@@ -345 +275 @@
 //
 
+        static $io_context * __ioarbiter_allocate( $io_arbiter & mutex this, processor *, __u32 idxs[], __u32 want );
+        static void __ioarbiter_submit  ( $io_arbiter & mutex this, $io_context * , __u32 idxs[], __u32 have );
+        static void __ioarbiter_flush   ( $io_arbiter & mutex this, $io_context * );
+        static inline void __ioarbiter_notify( $io_context & ctx );
+
+        //=============================================================================================
+        // Allocation
+        // for user's convenience fill the sqes from the indexes
+        static inline void __fill(struct io_uring_sqe * out_sqes[], __u32 want, __u32 idxs[], struct $io_context * ctx)  {
+                struct io_uring_sqe * sqes = ctx->sq.sqes;
+                for(i; want) {
+                        out_sqes[i] = &sqes[idxs[i]];
+                }
+        }
+
+        // Try to directly allocate from the a given context
+        // Not thread-safe
+        static inline bool __alloc(struct $io_context * ctx, __u32 idxs[], __u32 want) {
+                __sub_ring_t & sq = ctx->sq;
+                const __u32 mask  = *sq.mask;
+                __u32 fhead = sq.free_ring.head;    // get the current head of the queue
+                __u32 ftail = sq.free_ring.tail;    // get the current tail of the queue
+
+                // If we don't have enough sqes, fail
+                if((ftail - fhead) < want) { return false; }
+
+                // copy all the indexes we want from the available list
+                for(i; want) {
+                        idxs[i] = sq.free_ring.array[(fhead + i) & mask];
+                }
+
+                // Advance the head to mark the indexes as consumed
+                __atomic_store_n(&sq.free_ring.head, fhead + want, __ATOMIC_RELEASE);
+
+                // return success
+                return true;
+        }
+
         // Allocate an submit queue entry.
         // The kernel cannot see these entries until they are submitted, but other threads must be
@@ -350 +318 @@
         // for convenience, return both the index and the pointer to the sqe
         // sqe == &sqes[idx]
-        [* volatile struct io_uring_sqe, __u32] __submit_alloc( struct __io_data & ring, __u64 data ) {
-                /* paranoid */ verify( data != 0 );
-
-                // Prepare the data we need
-                __attribute((unused)) int len   = 0;
-                __attribute((unused)) int block = 0;
-                __u32 cnt = *ring.submit_q.num;
-                __u32 mask = *ring.submit_q.mask;
-
-                __u32 off = thread_rand();
-
-                // Loop around looking for an available spot
-                for() {
-                        // Look through the list starting at some offset
-                        for(i; cnt) {
-                                __u64 expected = 3;
-                                __u32 idx = (i + off) & mask; // Get an index from a random
-                                volatile struct io_uring_sqe * sqe = &ring.submit_q.sqes[idx];
-                                volatile __u64 * udata = &sqe->user_data;
-
-                                // Allocate the entry by CASing the user_data field from 0 to the future address
-                                if( *udata == expected &&
-                                        __atomic_compare_exchange_n( udata, &expected, data, true, __ATOMIC_SEQ_CST, __ATOMIC_RELAXED ) )
-                                {
-                                        // update statistics
-                                        __STATS__( false,
-                                                io.submit_q.alloc_avg.val   += len;
-                                                io.submit_q.alloc_avg.block += block;
-                                                io.submit_q.alloc_avg.cnt   += 1;
-                                        )
-
-                                        // debug log
-                                        __cfadbg_print_safe( io, "Kernel I/O : allocated [%p, %u] for %p (%p)\n", sqe, idx, active_thread(), (void*)data );
-
-                                        // Success return the data
-                                        return [sqe, idx];
-                                }
-                                verify(expected != data);
-
-                                // This one was used
-                                len ++;
-                        }
-
-                        block++;
-
-                        yield();
-                }
-        }
-
-        static inline __u32 __submit_to_ready_array( struct __io_data & ring, __u32 idx, const __u32 mask ) {
-                /* paranoid */ verify( idx <= mask   );
-                /* paranoid */ verify( idx != -1ul32 );
-
-                // We need to find a spot in the ready array
-                __attribute((unused)) int len   = 0;
-                __attribute((unused)) int block = 0;
-                __u32 ready_mask = ring.submit_q.ready_cnt - 1;
-
-                __u32 off = thread_rand();
-
-                __u32 picked;
-                LOOKING: for() {
-                        for(i; ring.submit_q.ready_cnt) {
-                                picked = (i + off) & ready_mask;
-                                __u32 expected = -1ul32;
-                                if( __atomic_compare_exchange_n( &ring.submit_q.ready[picked], &expected, idx, true, __ATOMIC_SEQ_CST, __ATOMIC_RELAXED ) ) {
-                                        break LOOKING;
-                                }
-                                verify(expected != idx);
-
-                                len ++;
-                        }
-
-                        block++;
-
-                        __u32 released = __release_consumed_submission( ring );
-                        if( released == 0 ) {
-                                yield();
-                        }
-                }
-
-                // update statistics
-                __STATS__( false,
-                        io.submit_q.look_avg.val   += len;
-                        io.submit_q.look_avg.block += block;
-                        io.submit_q.look_avg.cnt   += 1;
-                )
-
-                return picked;
-        }
-
-        void __submit( struct io_context * ctx, __u32 idx ) __attribute__((nonnull (1))) {
-                __io_data & ring = *ctx->thrd.ring;
-
+        struct $io_context * cfa_io_allocate(struct io_uring_sqe * sqes[], __u32 idxs[], __u32 want) {
+                __cfadbg_print_safe(io, "Kernel I/O : attempting to allocate %u\n", want);
+
+                disable_interrupts();
+                processor * proc = __cfaabi_tls.this_processor;
+                /* paranoid */ verify( __cfaabi_tls.this_processor );
+                /* paranoid */ verify( proc->io.lock == false );
+
+                __atomic_store_n( &proc->io.lock, true, __ATOMIC_SEQ_CST );
+                $io_context * ctx = proc->io.ctx;
+                $io_arbiter * ioarb = proc->cltr->io.arbiter;
+                /* paranoid */ verify( ioarb );
+
+                // Can we proceed to the fast path
+                if(  ctx                                // We alreay have an instance?
+                &&  !ctx->revoked )             // Our instance is still valid?
                 {
-                        __attribute__((unused)) volatile struct io_uring_sqe * sqe = &ring.submit_q.sqes[idx];
-                        __cfadbg_print_safe( io,
-                                "Kernel I/O : submitting %u (%p) for %p\n"
-                                "    data: %p\n"
-                                "    opcode: %s\n"
-                                "    fd: %d\n"
-                                "    flags: %d\n"
-                                "    prio: %d\n"
-                                "    off: %p\n"
-                                "    addr: %p\n"
-                                "    len: %d\n"
-                                "    other flags: %d\n"
-                                "    splice fd: %d\n"
-                                "    pad[0]: %llu\n"
-                                "    pad[1]: %llu\n"
-                                "    pad[2]: %llu\n",
-                                idx, sqe,
-                                active_thread(),
-                                (void*)sqe->user_data,
-                                opcodes[sqe->opcode],
-                                sqe->fd,
-                                sqe->flags,
-                                sqe->ioprio,
-                                (void*)sqe->off,
-                                (void*)sqe->addr,
-                                sqe->len,
-                                sqe->accept_flags,
-                                sqe->splice_fd_in,
-                                sqe->__pad2[0],
-                                sqe->__pad2[1],
-                                sqe->__pad2[2]
-                        );
-                }
-
-
-                // Get now the data we definetely need
-                volatile __u32 * const tail = ring.submit_q.tail;
-                const __u32 mask  = *ring.submit_q.mask;
-
-                // There are 2 submission schemes, check which one we are using
-                if( ring.poller_submits ) {
-                        // If the poller thread submits, then we just need to add this to the ready array
-                        __submit_to_ready_array( ring, idx, mask );
-
-                        post( ctx->thrd.sem );
-
-                        __cfadbg_print_safe( io, "Kernel I/O : Added %u to ready for %p\n", idx, active_thread() );
-                }
-                else if( ring.eager_submits ) {
-                        __attribute__((unused)) __u32 picked = __submit_to_ready_array( ring, idx, mask );
-
-                        #if defined(LEADER_LOCK)
-                                if( !try_lock(ring.submit_q.submit_lock) ) {
-                                        __STATS__( false,
-                                                io.submit_q.helped += 1;
-                                        )
-                                        return;
-                                }
-                                /* paranoid */ verify( ! __preemption_enabled() );
-                                __STATS__( true,
-                                        io.submit_q.leader += 1;
-                                )
-                        #else
-                                for() {
-                                        yield();
-
-                                        if( try_lock(ring.submit_q.submit_lock __cfaabi_dbg_ctx2) ) {
-                                                __STATS__( false,
-                                                        io.submit_q.leader += 1;
-                                                )
-                                                break;
-                                        }
-
-                                        // If some one else collected our index, we are done
-                                        #warning ABA problem
-                                        if( ring.submit_q.ready[picked] != idx ) {
-                                                __STATS__( false,
-                                                        io.submit_q.helped += 1;
-                                                )
-                                                return;
-                                        }
-
-                                        __STATS__( false,
-                                                io.submit_q.busy += 1;
-                                        )
-                                }
-                        #endif
-
-                        // We got the lock
-                        // Collect the submissions
-                        unsigned to_submit = __collect_submitions( ring );
-
-                        // Actually submit
-                        int ret = __io_uring_enter( ring, to_submit, false );
-
-                        #if defined(LEADER_LOCK)
-                                /* paranoid */ verify( ! __preemption_enabled() );
-                                next(ring.submit_q.submit_lock);
-                        #else
-                                unlock(ring.submit_q.submit_lock);
-                        #endif
-                        if( ret < 0 ) {
-                                return;
-                        }
-
-                        // Release the consumed SQEs
-                        __release_consumed_submission( ring );
-
-                        // update statistics
-                        __STATS__( false,
-                                io.submit_q.submit_avg.rdy += to_submit;
-                                io.submit_q.submit_avg.csm += ret;
-                                io.submit_q.submit_avg.cnt += 1;
-                        )
-
-                        __cfadbg_print_safe( io, "Kernel I/O : submitted %u (among %u) for %p\n", idx, ret, active_thread() );
-                }
-                else
+                        __cfadbg_print_safe(io, "Kernel I/O : attempting to fast allocation\n");
+
+                        // We can proceed to the fast path
+                        if( __alloc(ctx, idxs, want) ) {
+                                // Allocation was successful
+                                // Mark the instance as no longer in-use and re-enable interrupts
+                                __atomic_store_n( &proc->io.lock, false, __ATOMIC_RELEASE );
+                                enable_interrupts( __cfaabi_dbg_ctx );
+
+                                __cfadbg_print_safe(io, "Kernel I/O : fast allocation successful\n");
+
+                                __fill( sqes, want, idxs, ctx );
+                                return ctx;
+                        }
+                        // The fast path failed, fallback
+                }
+
+                // Fast path failed, fallback on arbitration
+                __atomic_store_n( &proc->io.lock, false, __ATOMIC_RELEASE );
+                enable_interrupts( __cfaabi_dbg_ctx );
+
+                __cfadbg_print_safe(io, "Kernel I/O : falling back on arbiter for allocation\n");
+
+                struct $io_context * ret = __ioarbiter_allocate(*ioarb, proc, idxs, want);
+
+                __cfadbg_print_safe(io, "Kernel I/O : slow allocation completed\n");
+
+                __fill( sqes, want, idxs,ret );
+                return ret;
+        }
+
+
+        //=============================================================================================
+        // submission
+        static inline void __submit( struct $io_context * ctx, __u32 idxs[], __u32 have) {
+                // We can proceed to the fast path
+                // Get the right objects
+                __sub_ring_t & sq = ctx->sq;
+                const __u32 mask  = *sq.mask;
+                __u32 tail = sq.kring.ready;
+
+                // Add the sqes to the array
+                for( i; have ) {
+                        sq.kring.array[ (tail + i) & mask ] = idxs[i];
+                }
+
+                // Make the sqes visible to the submitter
+                __atomic_store_n(&sq.kring.ready, tail + have, __ATOMIC_RELEASE);
+
+                // Make sure the poller is awake
+                __cfadbg_print_safe(io, "Kernel I/O : waking the poller\n");
+                post( ctx->sem );
+        }
+
+        void cfa_io_submit( struct $io_context * inctx, __u32 idxs[], __u32 have ) __attribute__((nonnull (1))) {
+                __cfadbg_print_safe(io, "Kernel I/O : attempting to submit %u\n", have);
+
+                disable_interrupts();
+                processor * proc = __cfaabi_tls.this_processor;
+                /* paranoid */ verify( __cfaabi_tls.this_processor );
+                /* paranoid */ verify( proc->io.lock == false );
+
+                __atomic_store_n( &proc->io.lock, true, __ATOMIC_SEQ_CST );
+                $io_context * ctx = proc->io.ctx;
+
+                // Can we proceed to the fast path
+                if(  ctx                                // We alreay have an instance?
+                &&  !ctx->revoked               // Our instance is still valid?
+                &&   ctx == inctx )             // We have the right instance?
                 {
-                        // get mutual exclusion
-                        #if defined(LEADER_LOCK)
-                                while(!try_lock(ring.submit_q.submit_lock));
-                        #else
-                                lock(ring.submit_q.submit_lock __cfaabi_dbg_ctx2);
-                        #endif
-
-                        /* paranoid */ verifyf( ring.submit_q.sqes[ idx ].user_data != 3ul64,
-                        /* paranoid */  "index %u already reclaimed\n"
-                        /* paranoid */  "head %u, prev %u, tail %u\n"
-                        /* paranoid */  "[-0: %u,-1: %u,-2: %u,-3: %u]\n",
-                        /* paranoid */  idx,
-                        /* paranoid */  *ring.submit_q.head, ring.submit_q.prev_head, *tail
-                        /* paranoid */  ,ring.submit_q.array[ ((*ring.submit_q.head) - 0) & (*ring.submit_q.mask) ]
-                        /* paranoid */  ,ring.submit_q.array[ ((*ring.submit_q.head) - 1) & (*ring.submit_q.mask) ]
-                        /* paranoid */  ,ring.submit_q.array[ ((*ring.submit_q.head) - 2) & (*ring.submit_q.mask) ]
-                        /* paranoid */  ,ring.submit_q.array[ ((*ring.submit_q.head) - 3) & (*ring.submit_q.mask) ]
-                        /* paranoid */ );
-
-                        // Append to the list of ready entries
-
-                        /* paranoid */ verify( idx <= mask );
-                        ring.submit_q.array[ (*tail) & mask ] = idx;
-                        __atomic_fetch_add(tail, 1ul32, __ATOMIC_SEQ_CST);
-
-                        // Submit however, many entries need to be submitted
-                        int ret = __io_uring_enter( ring, 1, false );
-                        if( ret < 0 ) {
-                                switch((int)errno) {
-                                default:
-                                        abort( "KERNEL ERROR: IO_URING SUBMIT - %s\n", strerror(errno) );
-                                }
-                        }
-
-                        /* paranoid */ verify(ret == 1);
-
-                        // update statistics
-                        __STATS__( false,
-                                io.submit_q.submit_avg.csm += 1;
-                                io.submit_q.submit_avg.cnt += 1;
-                        )
-
-                        {
-                                __attribute__((unused)) volatile __u32 * const head = ring.submit_q.head;
-                                __attribute__((unused)) __u32 last_idx = ring.submit_q.array[ ((*head) - 1) & mask ];
-                                __attribute__((unused)) volatile struct io_uring_sqe * sqe = &ring.submit_q.sqes[last_idx];
-
-                                __cfadbg_print_safe( io,
-                                        "Kernel I/O : last submitted is %u (%p)\n"
-                                        "    data: %p\n"
-                                        "    opcode: %s\n"
-                                        "    fd: %d\n"
-                                        "    flags: %d\n"
-                                        "    prio: %d\n"
-                                        "    off: %p\n"
-                                        "    addr: %p\n"
-                                        "    len: %d\n"
-                                        "    other flags: %d\n"
-                                        "    splice fd: %d\n"
-                                        "    pad[0]: %llu\n"
-                                        "    pad[1]: %llu\n"
-                                        "    pad[2]: %llu\n",
-                                        last_idx, sqe,
-                                        (void*)sqe->user_data,
-                                        opcodes[sqe->opcode],
-                                        sqe->fd,
-                                        sqe->flags,
-                                        sqe->ioprio,
-                                        (void*)sqe->off,
-                                        (void*)sqe->addr,
-                                        sqe->len,
-                                        sqe->accept_flags,
-                                        sqe->splice_fd_in,
-                                        sqe->__pad2[0],
-                                        sqe->__pad2[1],
-                                        sqe->__pad2[2]
-                                );
-                        }
-
-                        __atomic_thread_fence( __ATOMIC_SEQ_CST );
-                        // Release the consumed SQEs
-
-                        __release_consumed_submission( ring );
-                        // ring.submit_q.sqes[idx].user_data = 3ul64;
-
-                        #if defined(LEADER_LOCK)
-                                next(ring.submit_q.submit_lock);
-                        #else
-                                unlock(ring.submit_q.submit_lock);
-                        #endif
-
-                        __cfadbg_print_safe( io, "Kernel I/O : submitted %u for %p\n", idx, active_thread() );
-                }
-        }
-
-        // #define PARTIAL_SUBMIT 32
-
-        // go through the list of submissions in the ready array and moved them into
-        // the ring's submit queue
-        static unsigned __collect_submitions( struct __io_data & ring ) {
-                /* paranoid */ verify( ring.submit_q.ready != 0p );
-                /* paranoid */ verify( ring.submit_q.ready_cnt > 0 );
-
-                unsigned to_submit = 0;
-                __u32 tail = *ring.submit_q.tail;
-                const __u32 mask = *ring.submit_q.mask;
-                #if defined(PARTIAL_SUBMIT)
-                        #if defined(LEADER_LOCK)
-                                #error PARTIAL_SUBMIT and LEADER_LOCK cannot co-exist
-                        #endif
-                        const __u32 cnt = ring.submit_q.ready_cnt > PARTIAL_SUBMIT ? PARTIAL_SUBMIT : ring.submit_q.ready_cnt;
-                        const __u32 offset = ring.submit_q.prev_ready;
-                        ring.submit_q.prev_ready += cnt;
-                #else
-                        const __u32 cnt = ring.submit_q.ready_cnt;
-                        const __u32 offset = 0;
-                #endif
-
-                // Go through the list of ready submissions
-                for( c; cnt ) {
-                        __u32 i = (offset + c) % ring.submit_q.ready_cnt;
-
-                        // replace any submission with the sentinel, to consume it.
-                        __u32 idx = __atomic_exchange_n( &ring.submit_q.ready[i], -1ul32, __ATOMIC_RELAXED);
-
-                        // If it was already the sentinel, then we are done
-                        if( idx == -1ul32 ) continue;
-
-                        // If we got a real submission, append it to the list
-                        ring.submit_q.array[ (tail + to_submit) & mask ] = idx & mask;
-                        to_submit++;
-                }
-
-                // Increment the tail based on how many we are ready to submit
-                __atomic_fetch_add(ring.submit_q.tail, to_submit, __ATOMIC_SEQ_CST);
-
-                return to_submit;
-        }
+                        __submit(ctx, idxs, have);
+
+                        // Mark the instance as no longer in-use, re-enable interrupts and return
+                        __atomic_store_n( &proc->io.lock, false, __ATOMIC_RELEASE );
+                        enable_interrupts( __cfaabi_dbg_ctx );
+
+                        __cfadbg_print_safe(io, "Kernel I/O : submitted on fast path\n");
+                        return;
+                }
+
+                // Fast path failed, fallback on arbitration
+                __atomic_store_n( &proc->io.lock, false, __ATOMIC_RELEASE );
+                enable_interrupts( __cfaabi_dbg_ctx );
+
+                __cfadbg_print_safe(io, "Kernel I/O : falling back on arbiter for submission\n");
+
+                __ioarbiter_submit(*inctx->arbiter, inctx, idxs, have);
+        }
+
+        //=============================================================================================
+        // Flushing
+        static unsigned __flush( struct $io_context & ctx ) {
+                // First check for external
+                if( !__atomic_load_n(&ctx.ext_sq.empty, __ATOMIC_SEQ_CST) ) {
+                        // We have external submissions, delegate to the arbiter
+                        __ioarbiter_flush( *ctx.arbiter, &ctx );
+                }
+
+                __u32 tail  = *ctx.sq.kring.tail;
+                __u32 ready = ctx.sq.kring.ready;
+
+                /* paranoid */ verify( ctx.sq.to_submit <= *ctx.sq.num );
+                ctx.sq.to_submit += (ready - tail);
+                /* paranoid */ verify( ctx.sq.to_submit <= *ctx.sq.num );
+
+                if(ctx.sq.to_submit) {
+                        __cfadbg_print_safe(io, "Kernel I/O : %u ready to submit\n", ctx.sq.to_submit);
+                }
+
+                __atomic_store_n(ctx.sq.kring.tail, ready, __ATOMIC_RELEASE);
+
+                return ctx.sq.to_submit;
+        }
+
 
         // Go through the ring's submit queue and release everything that has already been consumed
         // by io_uring
-        static __u32 __release_consumed_submission( struct __io_data & ring ) {
-                const __u32 smask = *ring.submit_q.mask;
-
-                // We need to get the lock to copy the old head and new head
-                if( !try_lock(ring.submit_q.release_lock __cfaabi_dbg_ctx2) ) return 0;
+        // This cannot be done by multiple threads
+        static __u32 __release_sqes( struct $io_context & ctx ) {
+                const __u32 mask = *ctx.sq.mask;
+
                 __attribute__((unused))
-                __u32 ctail = *ring.submit_q.tail;        // get the current tail of the queue
-                __u32 chead = *ring.submit_q.head;              // get the current head of the queue
-                __u32 phead = ring.submit_q.prev_head;  // get the head the last time we were here
-                ring.submit_q.prev_head = chead;                // note up to were we processed
-                unlock(ring.submit_q.release_lock);
+                __u32 ctail = *ctx.sq.kring.tail;    // get the current tail of the queue
+                __u32 chead = *ctx.sq.kring.head;        // get the current head of the queue
+                __u32 phead = ctx.sq.kring.released; // get the head the last time we were here
+
+                __u32 ftail = ctx.sq.free_ring.tail;  // get the current tail of the queue
 
                 // the 3 fields are organized like this diagram
@@ -734 +480 @@
                 __u32 count = chead - phead;
 
+                if(count == 0) {
+                        return 0;
+                }
+
                 // We acquired an previous-head/current-head range
                 // go through the range and release the sqes
                 for( i; count ) {
-                        __u32 idx = ring.submit_q.array[ (phead + i) & smask ];
-
-                        /* paranoid */ verify( 0 != ring.submit_q.sqes[ idx ].user_data );
-                        __clean( &ring.submit_q.sqes[ idx ] );
-                }
+                        __u32 idx = ctx.sq.kring.array[ (phead + i) & mask ];
+                        ctx.sq.free_ring.array[ (ftail + i) & mask ] = idx;
+                }
+
+                ctx.sq.kring.released = chead;          // note up to were we processed
+                __atomic_store_n(&ctx.sq.free_ring.tail, ftail + count, __ATOMIC_SEQ_CST);
+
+                __ioarbiter_notify(ctx);
+
                 return count;
         }
 
-        void __sqe_clean( volatile struct io_uring_sqe * sqe ) {
-                __clean( sqe );
-        }
-
-        static inline void __clean( volatile struct io_uring_sqe * sqe ) {
-                // If we are in debug mode, thrash the fields to make sure we catch reclamation errors
-                __cfaabi_dbg_debug_do(
-                        memset(sqe, 0xde, sizeof(*sqe));
-                        sqe->opcode = (sizeof(opcodes) / sizeof(const char *)) - 1;
-                );
-
-                // Mark the entry as unused
-                __atomic_store_n(&sqe->user_data, 3ul64, __ATOMIC_SEQ_CST);
+//=============================================================================================
+// I/O Arbiter
+//=============================================================================================
+        static inline void __revoke( $io_arbiter & this, $io_context * ctx ) {
+                if(ctx->revoked) return;
+
+                remove( this.assigned, *ctx );
+
+                // Mark as revoked
+                __atomic_store_n(&ctx->revoked, true, __ATOMIC_SEQ_CST);
+
+                // Wait for the processor to no longer use it
+                while(ctx->proc->io.lock) Pause();
+
+                // Remove the coupling with the processor
+                ctx->proc->io.ctx = 0p;
+                ctx->proc = 0p;
+
+                // add to available contexts
+                addHead( this.available, *ctx );
+        }
+
+        static inline void __assign( $io_arbiter & this, $io_context * ctx, processor * proc ) {
+                remove( this.available, *ctx );
+
+                ctx->revoked = false;
+                ctx->proc = proc;
+                __atomic_store_n(&proc->io.ctx, ctx, __ATOMIC_SEQ_CST);
+
+                // add to assigned contexts
+                addTail( this.assigned, *ctx );
+        }
+
+        static $io_context * __ioarbiter_allocate( $io_arbiter & mutex this, processor * proc, __u32 idxs[], __u32 want ) {
+                __cfadbg_print_safe(io, "Kernel I/O : arbiter allocating\n");
+
+                SeqIter($io_context) iter;
+                $io_context & ci;
+                // Do we already have something available?
+                for( over( iter, this.available ); iter | ci;) {
+                        __cfadbg_print_safe(io, "Kernel I/O : attempting available context\n");
+
+                        $io_context * c = &ci;
+                        if(__alloc(c, idxs, want)) {
+                                __assign( this, c, proc);
+                                return c;
+                        }
+                }
+
+
+                // Otherwise, we have no choice but to revoke everyone to check if other instance have available data
+                for( over( iter, this.assigned ); iter | ci; ) {
+                        __cfadbg_print_safe(io, "Kernel I/O : revoking context for allocation\n");
+
+                        $io_context * c = &ci;
+                        __revoke( this, c );
+
+                        if(__alloc(c, idxs, want)) {
+                                __assign( this, c, proc);
+                                return c;
+                        }
+                }
+
+                __cfadbg_print_safe(io, "Kernel I/O : waiting for available resources\n");
+
+                // No one has any resources left, wait for something to finish
+                // Mark as pending
+                __atomic_store_n( &this.pending.flag, true, __ATOMIC_SEQ_CST );
+
+                // Wait for our turn to submit
+                wait( this.pending.blocked, want );
+
+                __attribute((unused)) bool ret =
+                __alloc( this.pending.ctx, idxs, want);
+                /* paranoid */ verify( ret );
+
+                __assign( this, this.pending.ctx, proc);
+                return this.pending.ctx;
+        }
+
+        static void __ioarbiter_notify( $io_arbiter & mutex this, $io_context * ctx ) {
+                /* paranoid */ verify( !is_empty(this.pending.blocked) );
+                this.pending.ctx = ctx;
+
+                while( !is_empty(this.pending.blocked) ) {
+                        __u32 have = ctx->sq.free_ring.tail - ctx->sq.free_ring.head;
+                        __u32 want = front( this.pending.blocked );
+
+                        if( have > want ) return;
+
+                        signal_block( this.pending.blocked );
+                }
+
+                this.pending.flag = false;
+        }
+
+        static void __ioarbiter_notify( $io_context & ctx ) {
+                if(__atomic_load_n( &ctx.arbiter->pending.flag, __ATOMIC_SEQ_CST)) {
+                        __ioarbiter_notify( *ctx.arbiter, &ctx );
+                }
+        }
+
+        // Simply append to the pending
+        static void __ioarbiter_submit( $io_arbiter & mutex this, $io_context * ctx, __u32 idxs[], __u32 have ) {
+                __cfadbg_print_safe(io, "Kernel I/O : submitting %u from the arbiter to context %u\n", have, ctx->fd);
+
+                /* paranoid */ verify( &this == ctx->arbiter );
+
+                // Mark as pending
+                __atomic_store_n( &ctx->ext_sq.empty, false, __ATOMIC_SEQ_CST );
+
+                // Wake-up the poller
+                post( ctx->sem );
+
+                __cfadbg_print_safe(io, "Kernel I/O : waiting to submit %u\n", have);
+
+                // Wait for our turn to submit
+                wait( ctx->ext_sq.blocked );
+
+                // Submit our indexes
+                __submit(ctx, idxs, have);
+
+                __cfadbg_print_safe(io, "Kernel I/O : %u submitted from arbiter\n", have);
+        }
+
+        static void __ioarbiter_flush( $io_arbiter & mutex this, $io_context * ctx ) {
+                /* paranoid */ verify( &this == ctx->arbiter );
+
+                __revoke( this, ctx );
+
+                __cfadbg_print_safe(io, "Kernel I/O : arbiter flushing\n");
+
+                condition & blcked = ctx->ext_sq.blocked;
+                /* paranoid */ verify( ctx->ext_sq.empty == is_empty( blcked ) );
+                while(!is_empty( blcked )) {
+                        signal_block( blcked );
+                }
+
+                ctx->ext_sq.empty = true;
+        }
+
+        void __ioarbiter_register( $io_arbiter & mutex this, $io_context & ctx ) {
+                __cfadbg_print_safe(io, "Kernel I/O : registering new context\n");
+
+                ctx.arbiter = &this;
+
+                // add to available contexts
+                addHead( this.available, ctx );
+
+                // Check if this solves pending allocations
+                if(this.pending.flag) {
+                        __ioarbiter_notify( ctx );
+                }
+        }
+
+        void __ioarbiter_unregister( $io_arbiter & mutex this, $io_context & ctx ) {
+                /* paranoid */ verify( &this == ctx.arbiter );
+
+                __revoke( this, &ctx );
+
+                remove( this.available, ctx );
         }
 #endif

libcfa/src/concurrency/io/call.cfa.in

@@ -54 +54 @@
                         | IOSQE_IO_DRAIN
                 #endif
+                #if defined(CFA_HAVE_IOSQE_IO_LINK)
+                        | IOSQE_IO_LINK
+                #endif
+                #if defined(CFA_HAVE_IOSQE_IO_HARDLINK)
+                        | IOSQE_IO_HARDLINK
+                #endif
                 #if defined(CFA_HAVE_IOSQE_ASYNC)
                         | IOSQE_ASYNC
                 #endif
-        ;
-
-        static const __u32 LINK_FLAGS = 0
-                #if defined(CFA_HAVE_IOSQE_IO_LINK)
-                        | IOSQE_IO_LINK
-                #endif
-                #if defined(CFA_HAVE_IOSQE_IO_HARDLINK)
-                        | IOSQE_IO_HARDLINK
+                #if defined(CFA_HAVE_IOSQE_BUFFER_SELECTED)
+                        | IOSQE_BUFFER_SELECTED
                 #endif
         ;
@@ -74 +74 @@
         ;
 
-        extern [* volatile struct io_uring_sqe, __u32] __submit_alloc( struct __io_data & ring, __u64 data );
-        extern void __submit( struct io_context * ctx, __u32 idx ) __attribute__((nonnull (1)));
-
-        static inline io_context * __get_io_context( void ) {
-                cluster * cltr = active_cluster();
-
-                /* paranoid */ verifyf( cltr, "No active cluster for io operation\\n");
-                assertf( cltr->io.cnt > 0, "Cluster %p has no default io contexts and no context was specified\\n", cltr );
-
-                /* paranoid */ verifyf( cltr->io.ctxs, "default io contexts for cluster %p are missing\\n", cltr);
-                return &cltr->io.ctxs[ thread_rand() % cltr->io.cnt ];
-        }
+        extern struct $io_context * cfa_io_allocate(struct io_uring_sqe * out_sqes[], __u32 out_idxs[], __u32 want)  __attribute__((nonnull (1,2)));
+        extern void cfa_io_submit( struct $io_context * in_ctx, __u32 in_idxs[], __u32 have ) __attribute__((nonnull (1,2)));
 #endif
 
@@ -195 +185 @@
                 return ', '.join(args_a)
 
-AsyncTemplate = """inline void async_{name}(io_future_t & future, {params}, int submit_flags, io_cancellation * cancellation, io_context * context) {{
+AsyncTemplate = """inline void async_{name}(io_future_t & future, {params}, int submit_flags) {{
         #if !defined(CFA_HAVE_LINUX_IO_URING_H) || !defined(CFA_HAVE_IORING_OP_{op})
                 ssize_t res = {name}({args});
@@ -205 +195 @@
                 }}
         #else
-                // we don't support LINK yet
-                if( 0 != (submit_flags & LINK_FLAGS) ) {{
-                        errno = ENOTSUP; return -1;
-                }}
-
-                if( !context ) {{
-                        context = __get_io_context();
-                }}
-                if(cancellation) {{
-                        cancellation->target = (__u64)(uintptr_t)&future;
-                }}
-
                 __u8 sflags = REGULAR_FLAGS & submit_flags;
-                struct __io_data & ring = *context->thrd.ring;
-
                 __u32 idx;
                 struct io_uring_sqe * sqe;
-                [(volatile struct io_uring_sqe *) sqe, idx] = __submit_alloc( ring, (__u64)(uintptr_t)&future );
+                struct $io_context * ctx = cfa_io_allocate( &sqe, &idx, 1 );
 
                 sqe->opcode = IORING_OP_{op};
+                sqe->user_data = (__u64)(uintptr_t)&future;
                 sqe->flags = sflags;
                 sqe->ioprio = 0;
@@ -239 +216 @@
 
                 verify( sqe->user_data == (__u64)(uintptr_t)&future );
-                __submit( context, idx );
+                cfa_io_submit( ctx, &idx, 1 );
         #endif
 }}"""
 
-SyncTemplate = """{ret} cfa_{name}({params}, int submit_flags, Duration timeout, io_cancellation * cancellation, io_context * context) {{
-        if( timeout >= 0 ) {{
-                errno = ENOTSUP;
-                return -1;
-        }}
+SyncTemplate = """{ret} cfa_{name}({params}, int submit_flags) {{
         io_future_t future;
 
-        async_{name}( future, {args}, submit_flags, cancellation, context );
+        async_{name}( future, {args}, submit_flags );
 
         wait( future );
@@ -415 +388 @@
         if c.define:
                 print("""#if defined({define})
-        {ret} cfa_{name}({params}, int submit_flags, Duration timeout, io_cancellation * cancellation, io_context * context);
+        {ret} cfa_{name}({params}, int submit_flags);
 #endif""".format(define=c.define,ret=c.ret, name=c.name, params=c.params))
         else:
-                print("{ret} cfa_{name}({params}, int submit_flags, Duration timeout, io_cancellation * cancellation, io_context * context);"
+                print("{ret} cfa_{name}({params}, int submit_flags);"
                 .format(ret=c.ret, name=c.name, params=c.params))
 
@@ -426 +399 @@
         if c.define:
                 print("""#if defined({define})
-        void async_{name}(io_future_t & future, {params}, int submit_flags, io_cancellation * cancellation, io_context * context);
+        void async_{name}(io_future_t & future, {params}, int submit_flags);
 #endif""".format(define=c.define,name=c.name, params=c.params))
         else:
-                print("void async_{name}(io_future_t & future, {params}, int submit_flags, io_cancellation * cancellation, io_context * context);"
+                print("void async_{name}(io_future_t & future, {params}, int submit_flags);"
                 .format(name=c.name, params=c.params))
 print("\n")
@@ -474 +447 @@
 
 print("""
-//-----------------------------------------------------------------------------
-bool cancel(io_cancellation & this) {
-        #if !defined(CFA_HAVE_LINUX_IO_URING_H) || !defined(CFA_HAVE_IORING_OP_ASYNC_CANCEL)
-                return false;
-        #else
-                io_future_t future;
-
-                io_context * context = __get_io_context();
-
-                __u8 sflags = 0;
-                struct __io_data & ring = *context->thrd.ring;
-
-                __u32 idx;
-                volatile struct io_uring_sqe * sqe;
-                [sqe, idx] = __submit_alloc( ring, (__u64)(uintptr_t)&future );
-
-                sqe->__pad2[0] = sqe->__pad2[1] = sqe->__pad2[2] = 0;
-                sqe->opcode = IORING_OP_ASYNC_CANCEL;
-                sqe->flags = sflags;
-                sqe->addr = this.target;
-
-                verify( sqe->user_data == (__u64)(uintptr_t)&future );
-                __submit( context, idx );
-
-                wait(future);
-
-                if( future.result == 0 ) return true; // Entry found
-                if( future.result == -EALREADY) return true; // Entry found but in progress
-                if( future.result == -ENOENT ) return false; // Entry not found
-                return false;
-        #endif
-}
-
 //-----------------------------------------------------------------------------
 // Check if a function is has asynchronous

libcfa/src/concurrency/io/setup.cfa

@@ -36 +36 @@
         void ?{}(io_context_params & this) {}
 
-        void ?{}(io_context & this, struct cluster & cl) {}
-        void ?{}(io_context & this, struct cluster & cl, const io_context_params & params) {}
-
-        void ^?{}(io_context & this) {}
-        void ^?{}(io_context & this, bool cluster_context) {}
-
-        void register_fixed_files( io_context &, int *, unsigned ) {}
-        void register_fixed_files( cluster    &, int *, unsigned ) {}
+        void  ?{}($io_context & this, struct cluster & cl) {}
+        void ^?{}($io_context & this) {}
+
+        $io_arbiter * create(void) { return 0p; }
+        void destroy($io_arbiter *) {}
 
 #else
@@ -68 +65 @@
         void ?{}(io_context_params & this) {
                 this.num_entries = 256;
-                this.num_ready = 256;
-                this.submit_aff = -1;
-                this.eager_submits = false;
-                this.poller_submits = false;
-                this.poll_submit = false;
-                this.poll_complete = false;
         }
 
@@ -194 +185 @@
 
                         for(i; nfds) {
-                                $io_ctx_thread * io_ctx = ($io_ctx_thread *)(uintptr_t)events[i].data.u64;
+                                $io_context * io_ctx = ($io_context *)(uintptr_t)events[i].data.u64;
                                 /* paranoid */ verify( io_ctx );
-                                __cfadbg_print_safe(io_core, "Kernel I/O - epoll : Unparking io poller %d (%p)\n", io_ctx->ring->fd, io_ctx);
+                                __cfadbg_print_safe(io_core, "Kernel I/O - epoll : Unparking io poller %d (%p)\n", io_ctx->fd, io_ctx);
                                 #if !defined( __CFA_NO_STATISTICS__ )
                                         __cfaabi_tls.this_stats = io_ctx->self.curr_cluster->stats;
@@ -202 +193 @@
 
                                 eventfd_t v;
-                                eventfd_read(io_ctx->ring->efd, &v);
+                                eventfd_read(io_ctx->efd, &v);
 
                                 post( io_ctx->sem );
@@ -219 +210 @@
 //=============================================================================================
 
-        void ?{}($io_ctx_thread & this, struct cluster & cl) { (this.self){ "IO Poller", cl }; }
-        void main( $io_ctx_thread & this );
-        static inline $thread * get_thread( $io_ctx_thread & this ) { return &this.self; }
-        void ^?{}( $io_ctx_thread & mutex this ) {}
-
-        static void __io_create ( __io_data & this, const io_context_params & params_in );
-        static void __io_destroy( __io_data & this );
-
-        void ?{}(io_context & this, struct cluster & cl, const io_context_params & params) {
-                (this.thrd){ cl };
-                this.thrd.ring = malloc();
-                __cfadbg_print_safe(io_core, "Kernel I/O : Creating ring for io_context %p\n", &this);
-                __io_create( *this.thrd.ring, params );
-
-                __cfadbg_print_safe(io_core, "Kernel I/O : Starting poller thread for io_context %p\n", &this);
-                this.thrd.done = false;
-                __thrd_start( this.thrd, main );
-
-                __cfadbg_print_safe(io_core, "Kernel I/O : io_context %p ready\n", &this);
+        static void __io_uring_setup ( $io_context & this, const io_context_params & params_in );
+        static void __io_uring_teardown( $io_context & this );
+        static void __epoll_register($io_context & ctx);
+        static void __epoll_unregister($io_context & ctx);
+        void __ioarbiter_register( $io_arbiter & mutex, $io_context & ctx );
+        void __ioarbiter_unregister( $io_arbiter & mutex, $io_context & ctx );
+
+        void ?{}($io_context & this, struct cluster & cl) {
+                (this.self){ "IO Poller", cl };
+                this.ext_sq.empty = true;
+                __io_uring_setup( this, cl.io.params );
+                __cfadbg_print_safe(io_core, "Kernel I/O : Created ring for io_context %u (%p)\n", this.fd, &this);
+
+                __epoll_register(this);
+
+                __ioarbiter_register(*cl.io.arbiter, this);
+
+                __thrd_start( this, main );
+                __cfadbg_print_safe(io_core, "Kernel I/O : Started poller thread for io_context %u\n", this.fd);
+        }
+
+        void ^?{}($io_context & mutex this) {
+                __cfadbg_print_safe(io_core, "Kernel I/O : tearing down io_context %u\n", this.fd);
+
+                ^(this.self){};
+                __cfadbg_print_safe(io_core, "Kernel I/O : Stopped poller thread for io_context %u\n", this.fd);
+
+                __ioarbiter_unregister(*this.arbiter, this);
+
+                __epoll_unregister(this);
+
+                __io_uring_teardown( this );
+                __cfadbg_print_safe(io_core, "Kernel I/O : Destroyed ring for io_context %u\n", this.fd);
         }
 
         void ?{}(io_context & this, struct cluster & cl) {
-                io_context_params params;
-                (this){ cl, params };
-        }
-
-        void ^?{}(io_context & this, bool cluster_context) {
-                __cfadbg_print_safe(io_core, "Kernel I/O : tearing down io_context %p\n", &this);
-
-                // Notify the thread of the shutdown
-                __atomic_store_n(&this.thrd.done, true, __ATOMIC_SEQ_CST);
-
-                // If this is an io_context within a cluster, things get trickier
-                $thread & thrd = this.thrd.self;
-                if( cluster_context ) {
-                        // We are about to do weird things with the threads
-                        // we don't need interrupts to complicate everything
-                        disable_interrupts();
-
-                        // Get cluster info
-                        cluster & cltr = *thrd.curr_cluster;
-                        /* paranoid */ verify( cltr.idles.total == 0 || &cltr == mainCluster );
-                        /* paranoid */ verify( !ready_mutate_islocked() );
-
-                        // We need to adjust the clean-up based on where the thread is
-                        if( thrd.state == Ready || thrd.preempted != __NO_PREEMPTION ) {
-                                // This is the tricky case
-                                // The thread was preempted or ready to run and now it is on the ready queue
-                                // but the cluster is shutting down, so there aren't any processors to run the ready queue
-                                // the solution is to steal the thread from the ready-queue and pretend it was blocked all along
-
-                                ready_schedule_lock();
-                                        // The thread should on the list
-                                        /* paranoid */ verify( thrd.link.next != 0p );
-
-                                        // Remove the thread from the ready queue of this cluster
-                                        // The thread should be the last on the list
-                                        __attribute__((unused)) bool removed = remove_head( &cltr, &thrd );
-                                        /* paranoid */ verify( removed );
-                                        thrd.link.next = 0p;
-                                        thrd.link.prev = 0p;
-
-                                        // Fixup the thread state
-                                        thrd.state = Blocked;
-                                        thrd.ticket = TICKET_BLOCKED;
-                                        thrd.preempted = __NO_PREEMPTION;
-
-                                ready_schedule_unlock();
-
-                                // Pretend like the thread was blocked all along
-                        }
-                        // !!! This is not an else if !!!
-                        // Ok, now the thread is blocked (whether we cheated to get here or not)
-                        if( thrd.state == Blocked ) {
-                                // This is the "easy case"
-                                // The thread is parked and can easily be moved to active cluster
-                                verify( thrd.curr_cluster != active_cluster() || thrd.curr_cluster == mainCluster );
-                                thrd.curr_cluster = active_cluster();
-
-                                // unpark the fast io_poller
-                                unpark( &thrd );
-                        }
-                        else {
-                                // The thread is in a weird state
-                                // I don't know what to do here
-                                abort("io_context poller thread is in unexpected state, cannot clean-up correctly\n");
-                        }
-
-                        // The weird thread kidnapping stuff is over, restore interrupts.
-                        enable_interrupts( __cfaabi_dbg_ctx );
-                } else {
-                        post( this.thrd.sem );
-                }
-
-                ^(this.thrd){};
-                __cfadbg_print_safe(io_core, "Kernel I/O : Stopped poller thread for io_context %p\n", &this);
-
-                __io_destroy( *this.thrd.ring );
-                __cfadbg_print_safe(io_core, "Kernel I/O : Destroyed ring for io_context %p\n", &this);
-
-                free(this.thrd.ring);
+                // this.ctx = new(cl);
+                this.ctx = alloc();
+                (*this.ctx){ cl };
+
+                __cfadbg_print_safe(io_core, "Kernel I/O : io_context %u ready\n", this.ctx->fd);
         }
 
         void ^?{}(io_context & this) {
-                ^(this){ false };
+                post( this.ctx->sem );
+
+                delete(this.ctx);
         }
 
@@ -329 +262 @@
         extern void __enable_interrupts_hard();
 
-        static void __io_create( __io_data & this, const io_context_params & params_in ) {
+        static void __io_uring_setup( $io_context & this, const io_context_params & params_in ) {
                 // Step 1 : call to setup
                 struct io_uring_params params;
                 memset(&params, 0, sizeof(params));
-                if( params_in.poll_submit   ) params.flags |= IORING_SETUP_SQPOLL;
-                if( params_in.poll_complete ) params.flags |= IORING_SETUP_IOPOLL;
+                // if( params_in.poll_submit   ) params.flags |= IORING_SETUP_SQPOLL;
+                // if( params_in.poll_complete ) params.flags |= IORING_SETUP_IOPOLL;
 
                 __u32 nentries = params_in.num_entries != 0 ? params_in.num_entries : 256;
@@ -340 +273 @@
                         abort("ERROR: I/O setup 'num_entries' must be a power of 2\n");
                 }
-                if( params_in.poller_submits && params_in.eager_submits ) {
-                        abort("ERROR: I/O setup 'poller_submits' and 'eager_submits' cannot be used together\n");
-                }
 
                 int fd = syscall(__NR_io_uring_setup, nentries, &params );
@@ -350 +280 @@
 
                 // Step 2 : mmap result
-                memset( &this, 0, sizeof(struct __io_data) );
-                struct __submition_data  & sq = this.submit_q;
-                struct __completion_data & cq = this.completion_q;
+                struct __sub_ring_t & sq = this.sq;
+                struct __cmp_ring_t & cq = this.cq;
 
                 // calculate the right ring size
@@ -401 +330 @@
                 // Get the pointers from the kernel to fill the structure
                 // submit queue
-                sq.head    = (volatile __u32 *)(((intptr_t)sq.ring_ptr) + params.sq_off.head);
-                sq.tail    = (volatile __u32 *)(((intptr_t)sq.ring_ptr) + params.sq_off.tail);
-                sq.mask    = (   const __u32 *)(((intptr_t)sq.ring_ptr) + params.sq_off.ring_mask);
-                sq.num     = (   const __u32 *)(((intptr_t)sq.ring_ptr) + params.sq_off.ring_entries);
-                sq.flags   = (         __u32 *)(((intptr_t)sq.ring_ptr) + params.sq_off.flags);
-                sq.dropped = (         __u32 *)(((intptr_t)sq.ring_ptr) + params.sq_off.dropped);
-                sq.array   = (         __u32 *)(((intptr_t)sq.ring_ptr) + params.sq_off.array);
-                sq.prev_head = *sq.head;
-
-                {
-                        const __u32 num = *sq.num;
-                        for( i; num ) {
-                                __sqe_clean( &sq.sqes[i] );
-                        }
-                }
-
-                (sq.submit_lock){};
-                (sq.release_lock){};
-
-                if( params_in.poller_submits || params_in.eager_submits ) {
-                        /* paranoid */ verify( is_pow2( params_in.num_ready ) || (params_in.num_ready < 8) );
-                        sq.ready_cnt = max( params_in.num_ready, 8 );
-                        sq.ready = alloc( sq.ready_cnt, 64`align );
-                        for(i; sq.ready_cnt) {
-                                sq.ready[i] = -1ul32;
-                        }
-                        sq.prev_ready = 0;
-                }
-                else {
-                        sq.ready_cnt = 0;
-                        sq.ready = 0p;
-                        sq.prev_ready = 0;
-                }
+                sq.kring.head  = (volatile __u32 *)(((intptr_t)sq.ring_ptr) + params.sq_off.head);
+                sq.kring.tail  = (volatile __u32 *)(((intptr_t)sq.ring_ptr) + params.sq_off.tail);
+                sq.kring.array = (         __u32 *)(((intptr_t)sq.ring_ptr) + params.sq_off.array);
+                sq.mask        = (   const __u32 *)(((intptr_t)sq.ring_ptr) + params.sq_off.ring_mask);
+                sq.num         = (   const __u32 *)(((intptr_t)sq.ring_ptr) + params.sq_off.ring_entries);
+                sq.flags       = (         __u32 *)(((intptr_t)sq.ring_ptr) + params.sq_off.flags);
+                sq.dropped     = (         __u32 *)(((intptr_t)sq.ring_ptr) + params.sq_off.dropped);
+
+                sq.kring.ready = 0;
+                sq.kring.released = 0;
+
+                sq.free_ring.head = 0;
+                sq.free_ring.tail = *sq.num;
+                sq.free_ring.array = alloc( *sq.num, 128`align );
+                for(i; (__u32)*sq.num) {
+                        sq.free_ring.array[i] = i;
+                }
+
+                sq.to_submit = 0;
 
                 // completion queue
@@ -468 +383 @@
                 /* paranoid */ verifyf( (*sq.mask) == ((*sq.num) - 1ul32), "IO_URING Expected mask to be %u (%u entries), was %u", (*sq.num) - 1ul32, *sq.num, *sq.mask );
                 /* paranoid */ verifyf( (*sq.num) >= nentries, "IO_URING Expected %u entries, got %u", nentries, *sq.num );
-                /* paranoid */ verifyf( (*sq.head) == 0, "IO_URING Expected head to be 0, got %u", *sq.head );
-                /* paranoid */ verifyf( (*sq.tail) == 0, "IO_URING Expected tail to be 0, got %u", *sq.tail );
+                /* paranoid */ verifyf( (*sq.kring.head) == 0, "IO_URING Expected head to be 0, got %u", *sq.kring.head );
+                /* paranoid */ verifyf( (*sq.kring.tail) == 0, "IO_URING Expected tail to be 0, got %u", *sq.kring.tail );
 
                 // Update the global ring info
-                this.ring_flags = params.flags;
+                this.ring_flags = 0;
                 this.fd         = fd;
                 this.efd        = efd;
-                this.eager_submits  = params_in.eager_submits;
-                this.poller_submits = params_in.poller_submits;
-        }
-
-        static void __io_destroy( __io_data & this ) {
+        }
+
+        static void __io_uring_teardown( $io_context & this ) {
                 // Shutdown the io rings
-                struct __submition_data  & sq = this.submit_q;
-                struct __completion_data & cq = this.completion_q;
+                struct __sub_ring_t & sq = this.sq;
+                struct __cmp_ring_t & cq = this.cq;
 
                 // unmap the submit queue entries
@@ -499 +412 @@
                 close(this.efd);
 
-                free( this.submit_q.ready ); // Maybe null, doesn't matter
+                free( this.sq.free_ring.array ); // Maybe null, doesn't matter
         }
 
@@ -505 +418 @@
 // I/O Context Sleep
 //=============================================================================================
-        static inline void __ioctx_epoll_ctl($io_ctx_thread & ctx, int op, const char * error) {
+        static inline void __epoll_ctl($io_context & ctx, int op, const char * error) {
                 struct epoll_event ev;
                 ev.events = EPOLLIN | EPOLLONESHOT;
                 ev.data.u64 = (__u64)&ctx;
-                int ret = epoll_ctl(iopoll.epollfd, op, ctx.ring->efd, &ev);
+                int ret = epoll_ctl(iopoll.epollfd, op, ctx.efd, &ev);
                 if (ret < 0) {
                         abort( "KERNEL ERROR: EPOLL %s - (%d) %s\n", error, (int)errno, strerror(errno) );
@@ -515 +428 @@
         }
 
-        void __ioctx_register($io_ctx_thread & ctx) {
-                __ioctx_epoll_ctl(ctx, EPOLL_CTL_ADD, "ADD");
-        }
-
-        void __ioctx_prepare_block($io_ctx_thread & ctx) {
-                __cfadbg_print_safe(io_core, "Kernel I/O - epoll : Re-arming io poller %d (%p)\n", ctx.ring->fd, &ctx);
-                __ioctx_epoll_ctl(ctx, EPOLL_CTL_MOD, "REARM");
-        }
-
-        void __ioctx_unregister($io_ctx_thread & ctx) {
+        static void __epoll_register($io_context & ctx) {
+                __epoll_ctl(ctx, EPOLL_CTL_ADD, "ADD");
+        }
+
+        static void __epoll_unregister($io_context & ctx) {
                 // Read the current epoch so we know when to stop
                 size_t curr = __atomic_load_n(&iopoll.epoch, __ATOMIC_SEQ_CST);
 
                 // Remove the fd from the iopoller
-                __ioctx_epoll_ctl(ctx, EPOLL_CTL_DEL, "REMOVE");
+                __epoll_ctl(ctx, EPOLL_CTL_DEL, "REMOVE");
 
                 // Notify the io poller thread of the shutdown
@@ -543 +451 @@
         }
 
+        void __ioctx_prepare_block($io_context & ctx) {
+                __cfadbg_print_safe(io_core, "Kernel I/O - epoll : Re-arming io poller %d (%p)\n", ctx.fd, &ctx);
+                __epoll_ctl(ctx, EPOLL_CTL_MOD, "REARM");
+        }
+
+
 //=============================================================================================
 // I/O Context Misc Setup
 //=============================================================================================
-        void register_fixed_files( io_context & ctx, int * files, unsigned count ) {
-                int ret = syscall( __NR_io_uring_register, ctx.thrd.ring->fd, IORING_REGISTER_FILES, files, count );
-                if( ret < 0 ) {
-                        abort( "KERNEL ERROR: IO_URING REGISTER - (%d) %s\n", (int)errno, strerror(errno) );
-                }
-
-                __cfadbg_print_safe( io_core, "Kernel I/O : Performed io_register for %p, returned %d\n", active_thread(), ret );
-        }
-
-        void register_fixed_files( cluster & cltr, int * files, unsigned count ) {
-                for(i; cltr.io.cnt) {
-                        register_fixed_files( cltr.io.ctxs[i], files, count );
-                }
-        }
+        void ?{}( $io_arbiter & this ) {
+                this.pending.flag = false;
+        }
+
+        void ^?{}( $io_arbiter & mutex this ) {
+                /* paranoid */ verify( empty(this.assigned) );
+                /* paranoid */ verify( empty(this.available) );
+                /* paranoid */ verify( is_empty(this.pending.blocked) );
+        }
+
+        $io_arbiter * create(void) {
+                return new();
+        }
+        void destroy($io_arbiter * arbiter) {
+                delete(arbiter);
+        }
+
+//=============================================================================================
+// I/O Context Misc Setup
+//=============================================================================================
+
 #endif

libcfa/src/concurrency/io/types.hfa

@@ -25 +25 @@
 
 #if defined(CFA_HAVE_LINUX_IO_URING_H)
-        #define LEADER_LOCK
-        struct __leaderlock_t {
-                struct $thread * volatile value;        // ($thread) next_leader | (bool:1) is_locked
-        };
+        #include "bits/sequence.hfa"
+        #include "monitor.hfa"
 
-        static inline void ?{}( __leaderlock_t & this ) { this.value = 0p; }
+        struct processor;
+        monitor $io_arbiter;
 
         //-----------------------------------------------------------------------
         // Ring Data structure
-      struct __submition_data {
-                // Head and tail of the ring (associated with array)
-                volatile __u32 * head;
-                volatile __u32 * tail;
-                volatile __u32 prev_head;
+      struct __sub_ring_t {
+                struct {
+                        // Head and tail of the ring (associated with array)
+                        volatile __u32 * head;   // one passed last index consumed by the kernel
+                        volatile __u32 * tail;   // one passed last index visible to the kernel
+                        volatile __u32 ready;    // one passed last index added to array ()
+                        volatile __u32 released; // one passed last index released back to the free list
 
-                // The actual kernel ring which uses head/tail
-                // indexes into the sqes arrays
-                __u32 * array;
+                        // The actual kernel ring which uses head/tail
+                        // indexes into the sqes arrays
+                        __u32 * array;
+                } kring;
+
+                struct {
+                        volatile __u32 head;
+                        volatile __u32 tail;
+                        // The ring which contains free allocations
+                        // indexes into the sqes arrays
+                        __u32 * array;
+                } free_ring;
+
+                // number of sqes to submit on next system call.
+                __u32 to_submit;
 
                 // number of entries and mask to go with it
@@ -48 +61 @@
                 const __u32 * mask;
 
-                // Submission flags (Not sure what for)
+                // Submission flags, currently only IORING_SETUP_SQPOLL
                 __u32 * flags;
 
-                // number of sqes not submitted (whatever that means)
+                // number of sqes not submitted
+                // From documentation : [dropped] is incremented for each invalid submission queue entry encountered in the ring buffer.
                 __u32 * dropped;
 
-                // Like head/tail but not seen by the kernel
-                volatile __u32 * ready;
-                __u32 ready_cnt;
-                __u32 prev_ready;
-
-                #if defined(LEADER_LOCK)
-                        __leaderlock_t submit_lock;
-                #else
-                        __spinlock_t submit_lock;
-                #endif
-                __spinlock_t  release_lock;
-
                 // A buffer of sqes (not the actual ring)
-                volatile struct io_uring_sqe * sqes;
+                struct io_uring_sqe * sqes;
 
                 // The location and size of the mmaped area
@@ -74 +76 @@
         };
 
-        struct __completion_data {
+        struct __cmp_ring_t {
                 // Head and tail of the ring
                 volatile __u32 * head;
@@ -83 +85 @@
                 const __u32 * num;
 
-                // number of cqes not submitted (whatever that means)
+                // I don't know what this value is for
                 __u32 * overflow;
 
@@ -94 +96 @@
         };
 
-        struct __io_data {
-                struct __submition_data submit_q;
-                struct __completion_data completion_q;
+        struct __attribute__((aligned(128))) $io_context {
+                inline Seqable;
+
+                volatile bool revoked;
+                processor * proc;
+
+                $io_arbiter * arbiter;
+
+                struct {
+                        volatile bool empty;
+                        condition blocked;
+                } ext_sq;
+
+                struct __sub_ring_t sq;
+                struct __cmp_ring_t cq;
                 __u32 ring_flags;
                 int fd;
                 int efd;
-                bool eager_submits:1;
-                bool poller_submits:1;
+
+                single_sem sem;
+                $thread self;
+        };
+
+        void main( $io_context & this );
+        static inline $thread  * get_thread ( $io_context & this ) __attribute__((const)) { return &this.self; }
+        static inline $monitor * get_monitor( $io_context & this ) __attribute__((const)) { return &this.self.self_mon; }
+        static inline $io_context *& Back( $io_context * n ) { return ($io_context *)Back( (Seqable *)n ); }
+        static inline $io_context *& Next( $io_context * n ) { return ($io_context *)Next( (Colable *)n ); }
+        void ^?{}( $io_context & mutex this );
+
+        monitor __attribute__((aligned(128))) $io_arbiter {
+                struct {
+                        condition blocked;
+                        $io_context * ctx;
+                        volatile bool flag;
+                } pending;
+
+                Sequence($io_context) assigned;
+
+                Sequence($io_context) available;
         };
 
@@ -133 +167 @@
         #endif
 
-        struct $io_ctx_thread;
-        void __ioctx_register($io_ctx_thread & ctx);
-        void __ioctx_unregister($io_ctx_thread & ctx);
-        void __ioctx_prepare_block($io_ctx_thread & ctx);
-        void __sqe_clean( volatile struct io_uring_sqe * sqe );
+        void __ioctx_prepare_block($io_context & ctx);
 #endif
 

libcfa/src/concurrency/iofwd.hfa

@@ -48 +48 @@
 struct cluster;
 struct io_future_t;
-struct io_context;
-struct io_cancellation;
+struct $io_context;
 
 struct iovec;
@@ -55 +54 @@
 struct sockaddr;
 struct statx;
+struct epoll_event;
+
+//----------
+// underlying calls
+extern struct $io_context * cfa_io_allocate(struct io_uring_sqe * out_sqes[], __u32 out_idxs[], __u32 want)  __attribute__((nonnull (1,2)));
+extern void cfa_io_submit( struct $io_context * in_ctx, __u32 in_idxs[], __u32 have ) __attribute__((nonnull (1,2)));
 
 //----------
 // synchronous calls
 #if defined(CFA_HAVE_PREADV2)
-        extern ssize_t cfa_preadv2(int fd, const struct iovec *iov, int iovcnt, off_t offset, int flags, int submit_flags, Duration timeout, io_cancellation * cancellation, io_context * context);
+        extern ssize_t cfa_preadv2(int fd, const struct iovec *iov, int iovcnt, off_t offset, int flags, int submit_flags);
 #endif
 #if defined(CFA_HAVE_PWRITEV2)
-        extern ssize_t cfa_pwritev2(int fd, const struct iovec *iov, int iovcnt, off_t offset, int flags, int submit_flags, Duration timeout, io_cancellation * cancellation, io_context * context);
+        extern ssize_t cfa_pwritev2(int fd, const struct iovec *iov, int iovcnt, off_t offset, int flags, int submit_flags);
 #endif
-extern int cfa_fsync(int fd, int submit_flags, Duration timeout, io_cancellation * cancellation, io_context * context);
-extern int cfa_epoll_ctl(int epfd, int op, int fd, struct epoll_event *event, int submit_flags, Duration timeout, io_cancellation * cancellation, io_context * context);
-extern int cfa_sync_file_range(int fd, off64_t offset, off64_t nbytes, unsigned int flags, int submit_flags, Duration timeout, io_cancellation * cancellation, io_context * context);
-extern  ssize_t cfa_sendmsg(int sockfd, const struct msghdr *msg, int flags, int submit_flags, Duration timeout, io_cancellation * cancellation, io_context * context);
-extern ssize_t cfa_recvmsg(int sockfd, struct msghdr *msg, int flags, int submit_flags, Duration timeout, io_cancellation * cancellation, io_context * context);
-extern ssize_t cfa_send(int sockfd, const void *buf, size_t len, int flags, int submit_flags, Duration timeout, io_cancellation * cancellation, io_context * context);
-extern ssize_t cfa_recv(int sockfd, void *buf, size_t len, int flags, int submit_flags, Duration timeout, io_cancellation * cancellation, io_context * context);
-extern int cfa_accept4(int sockfd, struct sockaddr *addr, socklen_t *addrlen, int flags, int submit_flags, Duration timeout, io_cancellation * cancellation, io_context * context);
-extern int cfa_connect(int sockfd, const struct sockaddr *addr, socklen_t addrlen, int submit_flags, Duration timeout, io_cancellation * cancellation, io_context * context);
-extern int cfa_fallocate(int fd, int mode, off_t offset, off_t len, int submit_flags, Duration timeout, io_cancellation * cancellation, io_context * context);
-extern int cfa_posix_fadvise(int fd, off_t offset, off_t len, int advice, int submit_flags, Duration timeout, io_cancellation * cancellation, io_context * context);
-extern int cfa_madvise(void *addr, size_t length, int advice, int submit_flags, Duration timeout, io_cancellation * cancellation, io_context * context);
-extern int cfa_openat(int dirfd, const char *pathname, int flags, mode_t mode, int submit_flags, Duration timeout, io_cancellation * cancellation, io_context * context);
+extern int cfa_fsync(int fd, int submit_flags);
+extern int cfa_epoll_ctl(int epfd, int op, int fd, struct epoll_event *event, int submit_flags);
+extern int cfa_sync_file_range(int fd, off64_t offset, off64_t nbytes, unsigned int flags, int submit_flags);
+extern  ssize_t cfa_sendmsg(int sockfd, const struct msghdr *msg, int flags, int submit_flags);
+extern ssize_t cfa_recvmsg(int sockfd, struct msghdr *msg, int flags, int submit_flags);
+extern ssize_t cfa_send(int sockfd, const void *buf, size_t len, int flags, int submit_flags);
+extern ssize_t cfa_recv(int sockfd, void *buf, size_t len, int flags, int submit_flags);
+extern int cfa_accept4(int sockfd, struct sockaddr *addr, socklen_t *addrlen, int flags, int submit_flags);
+extern int cfa_connect(int sockfd, const struct sockaddr *addr, socklen_t addrlen, int submit_flags);
+extern int cfa_fallocate(int fd, int mode, off_t offset, off_t len, int submit_flags);
+extern int cfa_posix_fadvise(int fd, off_t offset, off_t len, int advice, int submit_flags);
+extern int cfa_madvise(void *addr, size_t length, int advice, int submit_flags);
+extern int cfa_openat(int dirfd, const char *pathname, int flags, mode_t mode, int submit_flags);
 #if defined(CFA_HAVE_OPENAT2)
-        extern int cfa_openat2(int dirfd, const char *pathname, struct open_how * how, size_t size, int submit_flags, Duration timeout, io_cancellation * cancellation, io_context * context);
+        extern int cfa_openat2(int dirfd, const char *pathname, struct open_how * how, size_t size, int submit_flags);
 #endif
-extern int cfa_close(int fd, int submit_flags, Duration timeout, io_cancellation * cancellation, io_context * context);
+extern int cfa_close(int fd, int submit_flags);
 #if defined(CFA_HAVE_STATX)
-        extern int cfa_statx(int dirfd, const char *pathname, int flags, unsigned int mask, struct statx *statxbuf, int submit_flags, Duration timeout, io_cancellation * cancellation, io_context * context);
+        extern int cfa_statx(int dirfd, const char *pathname, int flags, unsigned int mask, struct statx *statxbuf, int submit_flags);
 #endif
-extern ssize_t cfa_read(int fd, void * buf, size_t count, int submit_flags, Duration timeout, io_cancellation * cancellation, io_context * context);
-extern ssize_t cfa_write(int fd, void * buf, size_t count, int submit_flags, Duration timeout, io_cancellation * cancellation, io_context * context);
-extern ssize_t cfa_splice(int fd_in, loff_t *off_in, int fd_out, loff_t *off_out, size_t len, unsigned int flags, int submit_flags, Duration timeout, io_cancellation * cancellation, io_context * context);
-extern ssize_t cfa_tee(int fd_in, int fd_out, size_t len, unsigned int flags, int submit_flags, Duration timeout, io_cancellation * cancellation, io_context * context);
+extern ssize_t cfa_read(int fd, void * buf, size_t count, int submit_flags);
+extern ssize_t cfa_write(int fd, void * buf, size_t count, int submit_flags);
+extern ssize_t cfa_splice(int fd_in, loff_t *off_in, int fd_out, loff_t *off_out, size_t len, unsigned int flags, int submit_flags);
+extern ssize_t cfa_tee(int fd_in, int fd_out, size_t len, unsigned int flags, int submit_flags);
 
 //----------
 // asynchronous calls
 #if defined(CFA_HAVE_PREADV2)
-        extern void async_preadv2(io_future_t & future, int fd, const struct iovec *iov, int iovcnt, off_t offset, int flags, int submit_flags, io_cancellation * cancellation, io_context * context);
+        extern void async_preadv2(io_future_t & future, int fd, const struct iovec *iov, int iovcnt, off_t offset, int flags, int submit_flags);
 #endif
 #if defined(CFA_HAVE_PWRITEV2)
-        extern void async_pwritev2(io_future_t & future, int fd, const struct iovec *iov, int iovcnt, off_t offset, int flags, int submit_flags, io_cancellation * cancellation, io_context * context);
+        extern void async_pwritev2(io_future_t & future, int fd, const struct iovec *iov, int iovcnt, off_t offset, int flags, int submit_flags);
 #endif
-extern void async_fsync(io_future_t & future, int fd, int submit_flags, io_cancellation * cancellation, io_context * context);
-extern void async_epoll_ctl(io_future_t & future, int epfd, int op, int fd, struct epoll_event *event, int submit_flags, io_cancellation * cancellation, io_context * context);
-extern void async_sync_file_range(io_future_t & future, int fd, off64_t offset, off64_t nbytes, unsigned int flags, int submit_flags, io_cancellation * cancellation, io_context * context);
-extern void async_sendmsg(io_future_t & future, int sockfd, const struct msghdr *msg, int flags, int submit_flags, io_cancellation * cancellation, io_context * context);
-extern void async_recvmsg(io_future_t & future, int sockfd, struct msghdr *msg, int flags, int submit_flags, io_cancellation * cancellation, io_context * context);
-extern void async_send(io_future_t & future, int sockfd, const void *buf, size_t len, int flags, int submit_flags, io_cancellation * cancellation, io_context * context);
-extern void async_recv(io_future_t & future, int sockfd, void *buf, size_t len, int flags, int submit_flags, io_cancellation * cancellation, io_context * context);
-extern void async_accept4(io_future_t & future, int sockfd, struct sockaddr *addr, socklen_t *addrlen, int flags, int submit_flags, io_cancellation * cancellation, io_context * context);
-extern void async_connect(io_future_t & future, int sockfd, const struct sockaddr *addr, socklen_t addrlen, int submit_flags, io_cancellation * cancellation, io_context * context);
-extern void async_fallocate(io_future_t & future, int fd, int mode, off_t offset, off_t len, int submit_flags, io_cancellation * cancellation, io_context * context);
-extern void async_posix_fadvise(io_future_t & future, int fd, off_t offset, off_t len, int advice, int submit_flags, io_cancellation * cancellation, io_context * context);
-extern void async_madvise(io_future_t & future, void *addr, size_t length, int advice, int submit_flags, io_cancellation * cancellation, io_context * context);
-extern void async_openat(io_future_t & future, int dirfd, const char *pathname, int flags, mode_t mode, int submit_flags, io_cancellation * cancellation, io_context * context);
+extern void async_fsync(io_future_t & future, int fd, int submit_flags);
+extern void async_epoll_ctl(io_future_t & future, int epfd, int op, int fd, struct epoll_event *event, int submit_flags);
+extern void async_sync_file_range(io_future_t & future, int fd, off64_t offset, off64_t nbytes, unsigned int flags, int submit_flags);
+extern void async_sendmsg(io_future_t & future, int sockfd, const struct msghdr *msg, int flags, int submit_flags);
+extern void async_recvmsg(io_future_t & future, int sockfd, struct msghdr *msg, int flags, int submit_flags);
+extern void async_send(io_future_t & future, int sockfd, const void *buf, size_t len, int flags, int submit_flags);
+extern void async_recv(io_future_t & future, int sockfd, void *buf, size_t len, int flags, int submit_flags);
+extern void async_accept4(io_future_t & future, int sockfd, struct sockaddr *addr, socklen_t *addrlen, int flags, int submit_flags);
+extern void async_connect(io_future_t & future, int sockfd, const struct sockaddr *addr, socklen_t addrlen, int submit_flags);
+extern void async_fallocate(io_future_t & future, int fd, int mode, off_t offset, off_t len, int submit_flags);
+extern void async_posix_fadvise(io_future_t & future, int fd, off_t offset, off_t len, int advice, int submit_flags);
+extern void async_madvise(io_future_t & future, void *addr, size_t length, int advice, int submit_flags);
+extern void async_openat(io_future_t & future, int dirfd, const char *pathname, int flags, mode_t mode, int submit_flags);
 #if defined(CFA_HAVE_OPENAT2)
-        extern void async_openat2(io_future_t & future, int dirfd, const char *pathname, struct open_how * how, size_t size, int submit_flags, io_cancellation * cancellation, io_context * context);
+        extern void async_openat2(io_future_t & future, int dirfd, const char *pathname, struct open_how * how, size_t size, int submit_flags);
 #endif
-extern void async_close(io_future_t & future, int fd, int submit_flags, io_cancellation * cancellation, io_context * context);
+extern void async_close(io_future_t & future, int fd, int submit_flags);
 #if defined(CFA_HAVE_STATX)
-        extern void async_statx(io_future_t & future, int dirfd, const char *pathname, int flags, unsigned int mask, struct statx *statxbuf, int submit_flags, io_cancellation * cancellation, io_context * context);
+        extern void async_statx(io_future_t & future, int dirfd, const char *pathname, int flags, unsigned int mask, struct statx *statxbuf, int submit_flags);
 #endif
-void async_read(io_future_t & future, int fd, void * buf, size_t count, int submit_flags, io_cancellation * cancellation, io_context * context);
-extern void async_write(io_future_t & future, int fd, void * buf, size_t count, int submit_flags, io_cancellation * cancellation, io_context * context);
-extern void async_splice(io_future_t & future, int fd_in, loff_t *off_in, int fd_out, loff_t *off_out, size_t len, unsigned int flags, int submit_flags, io_cancellation * cancellation, io_context * context);
-extern void async_tee(io_future_t & future, int fd_in, int fd_out, size_t len, unsigned int flags, int submit_flags, io_cancellation * cancellation, io_context * context);
+void async_read(io_future_t & future, int fd, void * buf, size_t count, int submit_flags);
+extern void async_write(io_future_t & future, int fd, void * buf, size_t count, int submit_flags);
+extern void async_splice(io_future_t & future, int fd_in, loff_t *off_in, int fd_out, loff_t *off_out, size_t len, unsigned int flags, int submit_flags);
+extern void async_tee(io_future_t & future, int fd_in, int fd_out, size_t len, unsigned int flags, int submit_flags);
 
 
@@ -126 +131 @@
 // Check if a function is blocks a only the user thread
 bool has_user_level_blocking( fptr_t func );
-
-//-----------------------------------------------------------------------------
-void register_fixed_files( io_context & ctx , int * files, unsigned count );
-void register_fixed_files( cluster    & cltr, int * files, unsigned count );

libcfa/src/concurrency/kernel.hfa

@@ -41 +41 @@
 
 //-----------------------------------------------------------------------------
+// I/O
+struct cluster;
+struct $io_context;
+struct $io_arbiter;
+
+struct io_context_params {
+        int num_entries;
+};
+
+void  ?{}(io_context_params & this);
+
+struct io_context {
+        $io_context * ctx;
+        cluster * cltr;
+};
+void  ?{}(io_context & this, struct cluster & cl);
+void ^?{}(io_context & this);
+
+//-----------------------------------------------------------------------------
 // Processor
 extern struct cluster * mainCluster;
@@ -78 +97 @@
         pthread_t kernel_thread;
 
+        struct {
+                $io_context * volatile ctx;
+                volatile bool lock;
+        } io;
+
         // Preemption data
         // Node which is added in the discrete event simulaiton
@@ -116 +140 @@
 
 DLISTED_MGD_IMPL_OUT(processor)
-
-//-----------------------------------------------------------------------------
-// I/O
-struct __io_data;
-
-// IO poller user-thread
-// Not using the "thread" keyword because we want to control
-// more carefully when to start/stop it
-struct $io_ctx_thread {
-        struct __io_data * ring;
-        single_sem sem;
-        volatile bool done;
-        $thread self;
-};
-
-
-struct io_context {
-        $io_ctx_thread thrd;
-};
-
-struct io_context_params {
-        int num_entries;
-        int num_ready;
-        int submit_aff;
-        bool eager_submits:1;
-        bool poller_submits:1;
-        bool poll_submit:1;
-        bool poll_complete:1;
-};
-
-void  ?{}(io_context_params & this);
-
-void  ?{}(io_context & this, struct cluster & cl);
-void  ?{}(io_context & this, struct cluster & cl, const io_context_params & params);
-void ^?{}(io_context & this);
-
-struct io_cancellation {
-        __u64 target;
-};
-
-static inline void  ?{}(io_cancellation & this) { this.target = -1u; }
-static inline void ^?{}(io_cancellation &) {}
-bool cancel(io_cancellation & this);
 
 //-----------------------------------------------------------------------------
@@ -244 +225 @@
 
         struct {
-                io_context * ctxs;
-                unsigned cnt;
+                $io_arbiter * arbiter;
+                io_context_params params;
         } io;
 

libcfa/src/concurrency/kernel/startup.cfa

@@ -104 +104 @@
 KERNEL_STORAGE($thread,              mainThread);
 KERNEL_STORAGE(__stack_t,            mainThreadCtx);
-KERNEL_STORAGE(io_context,           mainPollerThread);
+KERNEL_STORAGE(io_context,           mainIoContext);
 KERNEL_STORAGE(__scheduler_RWLock_t, __scheduler_lock);
 #if !defined(__CFA_NO_STATISTICS__)
@@ -231 +231 @@
         __kernel_io_startup();
 
+        io_context * mainio = (io_context *)&storage_mainIoContext;
+        (*mainio){ *mainCluster };
+
         // Add the main thread to the ready queue
         // once resume is called on mainProcessor->runner the mainThread needs to be scheduled like any normal thread
@@ -243 +246 @@
         // THE SYSTEM IS NOW COMPLETELY RUNNING
 
-
-        // SKULLDUGGERY: The constructor for the mainCluster will call alloc with a dimension of 0
-        // malloc *can* return a non-null value, we should free it if that is the case
-        free( mainCluster->io.ctxs );
-
-        // Now that the system is up, finish creating systems that need threading
-        mainCluster->io.ctxs = (io_context *)&storage_mainPollerThread;
-        mainCluster->io.cnt  = 1;
-        (*mainCluster->io.ctxs){ *mainCluster };
-
         __cfadbg_print_safe(runtime_core, "Kernel : Started\n--------------------------------------------------\n\n");
 
@@ -263 +256 @@
 static void __kernel_shutdown(void) {
         //Before we start shutting things down, wait for systems that need threading to shutdown
-        ^(*mainCluster->io.ctxs){};
-        mainCluster->io.cnt  = 0;
-        mainCluster->io.ctxs = 0p;
+        io_context * mainio = (io_context *)&storage_mainIoContext;
+        ^(*mainio){};
 
         /* paranoid */ verify( __preemption_enabled() );
@@ -486 +478 @@
         pending_preemption = false;
 
+        this.io.ctx = 0p;
+        this.io.lock = false;
+
         #if !defined(__CFA_NO_STATISTICS__)
                 print_stats = 0;
@@ -584 +579 @@
         threads{ __get };
 
+        io.arbiter = create();
+        io.params = io_params;
+
         doregister(this);
 
@@ -596 +594 @@
         ready_mutate_unlock( last_size );
         enable_interrupts_noPoll(); // Don't poll, could be in main cluster
-
-
-        this.io.cnt  = num_io;
-        this.io.ctxs = aalloc(num_io);
-        for(i; this.io.cnt) {
-                (this.io.ctxs[i]){ this, io_params };
-        }
 }
 
 void ^?{}(cluster & this) {
-        for(i; this.io.cnt) {
-                ^(this.io.ctxs[i]){ true };
-        }
-        free(this.io.ctxs);
+        destroy(this.io.arbiter);
 
         // Lock the RWlock so no-one pushes/pops while we are changing the queue

libcfa/src/concurrency/kernel_private.hfa

@@ -77 +77 @@
 //-----------------------------------------------------------------------------
 // I/O
-void ^?{}(io_context & this, bool );
+$io_arbiter * create(void);
+void destroy($io_arbiter *);
 
 //=======================================================================