Changeset 6e2b04e for libcfa/src/concurrency

Timestamp:

Jun 8, 2022, 4:23:41 PM (2 years ago)

Author:

caparsons <caparson@…>

Branches:

ADT, ast-experimental, master, pthread-emulation, qualifiedEnum

Children:

7f0ac12, db7a3ad

Parents:

55422cf (diff), 720f2fe2 (diff)
Note: this is a merge changeset, the changes displayed below correspond to the merge itself.
Use the (diff) links above to see all the changes relative to each parent.

Message:

Merge branch 'master' of plg.uwaterloo.ca:software/cfa/cfa-cc

Location:

libcfa/src/concurrency

Files:

• io.cfa (modified) (1 diff)
• io/setup.cfa (modified) (1 diff)

libcfa/src/concurrency/io.cfa

@@ -159 +159 @@
 
                 const __u32 mask = *ctx->cq.mask;
+                const __u32 num  = *ctx->cq.num;
                 unsigned long long ts_prev = ctx->cq.ts;
-
-                // re-read the head and tail in case it already changed.
-                const __u32 head = *ctx->cq.head;
-                const __u32 tail = *ctx->cq.tail;
-                const __u32 count = tail - head;
-                __STATS__( false, io.calls.drain++; io.calls.completed += count; )
-
-                for(i; count) {
-                        unsigned idx = (head + i) & mask;
-                        volatile struct io_uring_cqe & cqe = ctx->cq.cqes[idx];
-
-                        /* paranoid */ verify(&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 );
-
-                        __kernel_unpark( fulfil( *future, cqe.res, false ), UNPARK_LOCAL );
-                }
-
-                unsigned long long ts_next = ctx->cq.ts = rdtscl();
-
-                // 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_store_n( ctx->cq.head, head + count, __ATOMIC_SEQ_CST );
-                ctx->proc->idle_wctx.drain_time = ts_next;
+                unsigned long long ts_next;
+
+                // We might need to do this multiple times if more events completed than can fit in the queue.
+                for() {
+                        // re-read the head and tail in case it already changed.
+                        const __u32 head = *ctx->cq.head;
+                        const __u32 tail = *ctx->cq.tail;
+                        const __u32 count = tail - head;
+                        __STATS__( false, io.calls.drain++; io.calls.completed += count; )
+
+                        for(i; count) {
+                                unsigned idx = (head + i) & mask;
+                                volatile struct io_uring_cqe & cqe = ctx->cq.cqes[idx];
+
+                                /* paranoid */ verify(&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 );
+
+                                __kernel_unpark( fulfil( *future, cqe.res, false ), UNPARK_LOCAL );
+                        }
+
+                        ts_next = ctx->cq.ts = rdtscl();
+
+                        // 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_store_n( ctx->cq.head, head + count, __ATOMIC_SEQ_CST );
+                        ctx->proc->idle_wctx.drain_time = ts_next;
+
+                        if(likely(count < num)) break;
+
+                        ioring_syscsll( *ctx, 0, IORING_ENTER_GETEVENTS);
+                }
 
                 __cfadbg_print_safe(io, "Kernel I/O : %u completed age %llu\n", count, ts_next);

libcfa/src/concurrency/io/setup.cfa

@@ -138 +138 @@
                 __u32 nentries = params_in.num_entries != 0 ? params_in.num_entries : 256;
                 if( !is_pow2(nentries) ) {
-                        abort("ERROR: I/O setup 'num_entries' must be a power of 2\n");
+                        abort("ERROR: I/O setup 'num_entries' must be a power of 2, was %u\n", nentries);
                 }