source: libcfa/src/concurrency/io.cfa@ 224916b

ADT ast-experimental enum forall-pointer-decay pthread-emulation qualifiedEnum
Last change on this file since 224916b was 175f9f4, checked in by Thierry Delisle <tdelisle@…>, 4 years ago

Merge branch 'master' of plg.uwaterloo.ca:software/cfa/cfa-cc
  • Property mode set to 100644
File size: 16.8 KB
Line 
1//
2// Cforall Version 1.0.0 Copyright (C) 2020 University of Waterloo
3//
4// The contents of this file are covered under the licence agreement in the
5// file "LICENCE" distributed with Cforall.
6//
7// io.cfa --
8//
9// Author : Thierry Delisle
10// Created On : Thu Apr 23 17:31:00 2020
11// Last Modified By :
12// Last Modified On :
13// Update Count :
14//
15
16#define __cforall_thread__
17#define _GNU_SOURCE
18
19#if defined(__CFA_DEBUG__)
20 // #define __CFA_DEBUG_PRINT_IO__
21 // #define __CFA_DEBUG_PRINT_IO_CORE__
22#endif
23
24
25#if defined(CFA_HAVE_LINUX_IO_URING_H)
26 #include <errno.h>
27 #include <signal.h>
28 #include <stdint.h>
29 #include <string.h>
30 #include <unistd.h>
31
32 extern "C" {
33 #include <sys/syscall.h>
34 #include <sys/eventfd.h>
35 #include <sys/uio.h>
36
37 #include <linux/io_uring.h>
38 }
39
40 #include "stats.hfa"
41 #include "kernel.hfa"
42 #include "kernel/fwd.hfa"
43 #include "kernel_private.hfa"
44 #include "io/types.hfa"
45
46 __attribute__((unused)) static const char * opcodes[] = {
47 "OP_NOP",
48 "OP_READV",
49 "OP_WRITEV",
50 "OP_FSYNC",
51 "OP_READ_FIXED",
52 "OP_WRITE_FIXED",
53 "OP_POLL_ADD",
54 "OP_POLL_REMOVE",
55 "OP_SYNC_FILE_RANGE",
56 "OP_SENDMSG",
57 "OP_RECVMSG",
58 "OP_TIMEOUT",
59 "OP_TIMEOUT_REMOVE",
60 "OP_ACCEPT",
61 "OP_ASYNC_CANCEL",
62 "OP_LINK_TIMEOUT",
63 "OP_CONNECT",
64 "OP_FALLOCATE",
65 "OP_OPENAT",
66 "OP_CLOSE",
67 "OP_FILES_UPDATE",
68 "OP_STATX",
69 "OP_READ",
70 "OP_WRITE",
71 "OP_FADVISE",
72 "OP_MADVISE",
73 "OP_SEND",
74 "OP_RECV",
75 "OP_OPENAT2",
76 "OP_EPOLL_CTL",
77 "OP_SPLICE",
78 "OP_PROVIDE_BUFFERS",
79 "OP_REMOVE_BUFFERS",
80 "OP_TEE",
81 "INVALID_OP"
82 };
83
84 static $io_context * __ioarbiter_allocate( $io_arbiter & this, __u32 idxs[], __u32 want );
85 static void __ioarbiter_submit( $io_context * , __u32 idxs[], __u32 have, bool lazy );
86 static void __ioarbiter_flush ( $io_context & );
87 static inline void __ioarbiter_notify( $io_context & ctx );
88//=============================================================================================
89// I/O Polling
90//=============================================================================================
91 static inline unsigned __flush( struct $io_context & );
92 static inline __u32 __release_sqes( struct $io_context & );
93 extern void __kernel_unpark( thread$ * thrd, unpark_hint );
94
95 bool __cfa_io_drain( processor * proc ) {
96 /* paranoid */ verify( ! __preemption_enabled() );
97 /* paranoid */ verify( ready_schedule_islocked() );
98 /* paranoid */ verify( proc );
99 /* paranoid */ verify( proc->io.ctx );
100
101 // Drain the queue
102 $io_context * ctx = proc->io.ctx;
103 unsigned head = *ctx->cq.head;
104 unsigned tail = *ctx->cq.tail;
105 const __u32 mask = *ctx->cq.mask;
106
107 __u32 count = tail - head;
108 __STATS__( false, io.calls.drain++; io.calls.completed += count; )
109
110 if(count == 0) return false;
111
112 for(i; count) {
113 unsigned idx = (head + i) & mask;
114 volatile struct io_uring_cqe & cqe = ctx->cq.cqes[idx];
115
116 /* paranoid */ verify(&cqe);
117
118 struct io_future_t * future = (struct io_future_t *)(uintptr_t)cqe.user_data;
119 __cfadbg_print_safe( io, "Kernel I/O : Syscall completed : cqe %p, result %d for %p\n", &cqe, cqe.res, future );
120
121 __kernel_unpark( fulfil( *future, cqe.res, false ), UNPARK_LOCAL );
122 }
123
124 __cfadbg_print_safe(io, "Kernel I/O : %u completed\n", count);
125
126 // Mark to the kernel that the cqe has been seen
127 // Ensure that the kernel only sees the new value of the head index after the CQEs have been read.
128 __atomic_store_n( ctx->cq.head, head + count, __ATOMIC_SEQ_CST );
129
130 /* paranoid */ verify( ready_schedule_islocked() );
131 /* paranoid */ verify( ! __preemption_enabled() );
132
133 return true;
134 }
135
136 bool __cfa_io_flush( processor * proc, int min_comp ) {
137 /* paranoid */ verify( ! __preemption_enabled() );
138 /* paranoid */ verify( proc );
139 /* paranoid */ verify( proc->io.ctx );
140
141 __attribute__((unused)) cluster * cltr = proc->cltr;
142 $io_context & ctx = *proc->io.ctx;
143
144 __ioarbiter_flush( ctx );
145
146 if(ctx.sq.to_submit != 0 || min_comp > 0) {
147
148 __STATS__( true, io.calls.flush++; )
149 int ret = syscall( __NR_io_uring_enter, ctx.fd, ctx.sq.to_submit, min_comp, min_comp > 0 ? IORING_ENTER_GETEVENTS : 0, (sigset_t *)0p, _NSIG / 8);
150 if( ret < 0 ) {
151 switch((int)errno) {
152 case EAGAIN:
153 case EINTR:
154 case EBUSY:
155 // Update statistics
156 __STATS__( false, io.calls.errors.busy ++; )
157 return false;
158 default:
159 abort( "KERNEL ERROR: IO_URING SYSCALL - (%d) %s\n", (int)errno, strerror(errno) );
160 }
161 }
162
163 __cfadbg_print_safe(io, "Kernel I/O : %u submitted to io_uring %d\n", ret, ctx.fd);
164 __STATS__( true, io.calls.submitted += ret; )
165 /* paranoid */ verify( ctx.sq.to_submit <= *ctx.sq.num );
166 /* paranoid */ verify( ctx.sq.to_submit >= ret );
167
168 ctx.sq.to_submit -= ret;
169
170 /* paranoid */ verify( ctx.sq.to_submit <= *ctx.sq.num );
171
172 // Release the consumed SQEs
173 __release_sqes( ctx );
174
175 /* paranoid */ verify( ! __preemption_enabled() );
176
177 ctx.proc->io.pending = false;
178 }
179
180 ready_schedule_lock();
181 bool ret = __cfa_io_drain( proc );
182 ready_schedule_unlock();
183 return ret;
184 }
185
186//=============================================================================================
187// I/O Submissions
188//=============================================================================================
189
190// Submition steps :
191// 1 - Allocate a queue entry. The ring already has memory for all entries but only the ones
192// listed in sq.array are visible by the kernel. For those not listed, the kernel does not
193// offer any assurance that an entry is not being filled by multiple flags. Therefore, we
194// need to write an allocator that allows allocating concurrently.
195//
196// 2 - Actually fill the submit entry, this is the only simple and straightforward step.
197//
198// 3 - Append the entry index to the array and adjust the tail accordingly. This operation
199// needs to arrive to two concensus at the same time:
200// A - The order in which entries are listed in the array: no two threads must pick the
201// same index for their entries
202// B - When can the tail be update for the kernel. EVERY entries in the array between
203// head and tail must be fully filled and shouldn't ever be touched again.
204//
205 //=============================================================================================
206 // Allocation
207 // for user's convenience fill the sqes from the indexes
208 static inline void __fill(struct io_uring_sqe * out_sqes[], __u32 want, __u32 idxs[], struct $io_context * ctx) {
209 struct io_uring_sqe * sqes = ctx->sq.sqes;
210 for(i; want) {
211 __cfadbg_print_safe(io, "Kernel I/O : filling loop\n");
212 out_sqes[i] = &sqes[idxs[i]];
213 }
214 }
215
216 // Try to directly allocate from the a given context
217 // Not thread-safe
218 static inline bool __alloc(struct $io_context * ctx, __u32 idxs[], __u32 want) {
219 __sub_ring_t & sq = ctx->sq;
220 const __u32 mask = *sq.mask;
221 __u32 fhead = sq.free_ring.head; // get the current head of the queue
222 __u32 ftail = sq.free_ring.tail; // get the current tail of the queue
223
224 // If we don't have enough sqes, fail
225 if((ftail - fhead) < want) { return false; }
226
227 // copy all the indexes we want from the available list
228 for(i; want) {
229 __cfadbg_print_safe(io, "Kernel I/O : allocating loop\n");
230 idxs[i] = sq.free_ring.array[(fhead + i) & mask];
231 }
232
233 // Advance the head to mark the indexes as consumed
234 __atomic_store_n(&sq.free_ring.head, fhead + want, __ATOMIC_RELEASE);
235
236 // return success
237 return true;
238 }
239
240 // Allocate an submit queue entry.
241 // The kernel cannot see these entries until they are submitted, but other threads must be
242 // able to see which entries can be used and which are already un used by an other thread
243 // for convenience, return both the index and the pointer to the sqe
244 // sqe == &sqes[idx]
245 struct $io_context * cfa_io_allocate(struct io_uring_sqe * sqes[], __u32 idxs[], __u32 want) {
246 __cfadbg_print_safe(io, "Kernel I/O : attempting to allocate %u\n", want);
247
248 disable_interrupts();
249 processor * proc = __cfaabi_tls.this_processor;
250 $io_context * ctx = proc->io.ctx;
251 /* paranoid */ verify( __cfaabi_tls.this_processor );
252 /* paranoid */ verify( ctx );
253
254 __cfadbg_print_safe(io, "Kernel I/O : attempting to fast allocation\n");
255
256 // We can proceed to the fast path
257 if( __alloc(ctx, idxs, want) ) {
258 // Allocation was successful
259 __STATS__( true, io.alloc.fast += 1; )
260 enable_interrupts();
261
262 __cfadbg_print_safe(io, "Kernel I/O : fast allocation successful from ring %d\n", ctx->fd);
263
264 __fill( sqes, want, idxs, ctx );
265 return ctx;
266 }
267 // The fast path failed, fallback
268 __STATS__( true, io.alloc.fail += 1; )
269
270 // Fast path failed, fallback on arbitration
271 __STATS__( true, io.alloc.slow += 1; )
272 enable_interrupts();
273
274 $io_arbiter * ioarb = proc->cltr->io.arbiter;
275 /* paranoid */ verify( ioarb );
276
277 __cfadbg_print_safe(io, "Kernel I/O : falling back on arbiter for allocation\n");
278
279 struct $io_context * ret = __ioarbiter_allocate(*ioarb, idxs, want);
280
281 __cfadbg_print_safe(io, "Kernel I/O : slow allocation completed from ring %d\n", ret->fd);
282
283 __fill( sqes, want, idxs,ret );
284 return ret;
285 }
286
287 //=============================================================================================
288 // submission
289 static inline void __submit( struct $io_context * ctx, __u32 idxs[], __u32 have, bool lazy) {
290 // We can proceed to the fast path
291 // Get the right objects
292 __sub_ring_t & sq = ctx->sq;
293 const __u32 mask = *sq.mask;
294 __u32 tail = *sq.kring.tail;
295
296 // Add the sqes to the array
297 for( i; have ) {
298 __cfadbg_print_safe(io, "Kernel I/O : __submit loop\n");
299 sq.kring.array[ (tail + i) & mask ] = idxs[i];
300 }
301
302 // Make the sqes visible to the submitter
303 __atomic_store_n(sq.kring.tail, tail + have, __ATOMIC_RELEASE);
304 sq.to_submit += have;
305
306 ctx->proc->io.pending = true;
307 ctx->proc->io.dirty = true;
308 if(sq.to_submit > 30 || !lazy) {
309 __cfa_io_flush( ctx->proc, 0 );
310 }
311 }
312
313 void cfa_io_submit( struct $io_context * inctx, __u32 idxs[], __u32 have, bool lazy ) __attribute__((nonnull (1))) {
314 __cfadbg_print_safe(io, "Kernel I/O : attempting to submit %u (%s)\n", have, lazy ? "lazy" : "eager");
315
316 disable_interrupts();
317 processor * proc = __cfaabi_tls.this_processor;
318 $io_context * ctx = proc->io.ctx;
319 /* paranoid */ verify( __cfaabi_tls.this_processor );
320 /* paranoid */ verify( ctx );
321
322 // Can we proceed to the fast path
323 if( ctx == inctx ) // We have the right instance?
324 {
325 __submit(ctx, idxs, have, lazy);
326
327 // Mark the instance as no longer in-use, re-enable interrupts and return
328 __STATS__( true, io.submit.fast += 1; )
329 enable_interrupts();
330
331 __cfadbg_print_safe(io, "Kernel I/O : submitted on fast path\n");
332 return;
333 }
334
335 // Fast path failed, fallback on arbitration
336 __STATS__( true, io.submit.slow += 1; )
337 enable_interrupts();
338
339 __cfadbg_print_safe(io, "Kernel I/O : falling back on arbiter for submission\n");
340
341 __ioarbiter_submit(inctx, idxs, have, lazy);
342 }
343
344 //=============================================================================================
345 // Flushing
346 // Go through the ring's submit queue and release everything that has already been consumed
347 // by io_uring
348 // This cannot be done by multiple threads
349 static __u32 __release_sqes( struct $io_context & ctx ) {
350 const __u32 mask = *ctx.sq.mask;
351
352 __attribute__((unused))
353 __u32 ctail = *ctx.sq.kring.tail; // get the current tail of the queue
354 __u32 chead = *ctx.sq.kring.head; // get the current head of the queue
355 __u32 phead = ctx.sq.kring.released; // get the head the last time we were here
356
357 __u32 ftail = ctx.sq.free_ring.tail; // get the current tail of the queue
358
359 // the 3 fields are organized like this diagram
360 // except it's are ring
361 // ---+--------+--------+----
362 // ---+--------+--------+----
363 // ^ ^ ^
364 // phead chead ctail
365
366 // make sure ctail doesn't wrap around and reach phead
367 /* paranoid */ verify(
368 (ctail >= chead && chead >= phead)
369 || (chead >= phead && phead >= ctail)
370 || (phead >= ctail && ctail >= chead)
371 );
372
373 // find the range we need to clear
374 __u32 count = chead - phead;
375
376 if(count == 0) {
377 return 0;
378 }
379
380 // We acquired an previous-head/current-head range
381 // go through the range and release the sqes
382 for( i; count ) {
383 __cfadbg_print_safe(io, "Kernel I/O : release loop\n");
384 __u32 idx = ctx.sq.kring.array[ (phead + i) & mask ];
385 ctx.sq.free_ring.array[ (ftail + i) & mask ] = idx;
386 }
387
388 ctx.sq.kring.released = chead; // note up to were we processed
389 __atomic_store_n(&ctx.sq.free_ring.tail, ftail + count, __ATOMIC_SEQ_CST);
390
391 __ioarbiter_notify(ctx);
392
393 return count;
394 }
395
396//=============================================================================================
397// I/O Arbiter
398//=============================================================================================
399 static inline void block(__outstanding_io_queue & queue, __outstanding_io & item) {
400 // Lock the list, it's not thread safe
401 lock( queue.lock __cfaabi_dbg_ctx2 );
402 {
403 // Add our request to the list
404 add( queue.queue, item );
405
406 // Mark as pending
407 __atomic_store_n( &queue.empty, false, __ATOMIC_SEQ_CST );
408 }
409 unlock( queue.lock );
410
411 wait( item.sem );
412 }
413
414 static inline bool empty(__outstanding_io_queue & queue ) {
415 return __atomic_load_n( &queue.empty, __ATOMIC_SEQ_CST);
416 }
417
418 static $io_context * __ioarbiter_allocate( $io_arbiter & this, __u32 idxs[], __u32 want ) {
419 __cfadbg_print_safe(io, "Kernel I/O : arbiter allocating\n");
420
421 __STATS__( false, io.alloc.block += 1; )
422
423 // No one has any resources left, wait for something to finish
424 // We need to add ourself to a list of pending allocs and wait for an answer
425 __pending_alloc pa;
426 pa.idxs = idxs;
427 pa.want = want;
428
429 block(this.pending, (__outstanding_io&)pa);
430
431 return pa.ctx;
432
433 }
434
435 static void __ioarbiter_notify( $io_arbiter & this, $io_context * ctx ) {
436 /* paranoid */ verify( !empty(this.pending.queue) );
437
438 lock( this.pending.lock __cfaabi_dbg_ctx2 );
439 {
440 while( !empty(this.pending.queue) ) {
441 __cfadbg_print_safe(io, "Kernel I/O : notifying\n");
442 __u32 have = ctx->sq.free_ring.tail - ctx->sq.free_ring.head;
443 __pending_alloc & pa = (__pending_alloc&)head( this.pending.queue );
444
445 if( have > pa.want ) goto DONE;
446 drop( this.pending.queue );
447
448 /* paranoid */__attribute__((unused)) bool ret =
449
450 __alloc(ctx, pa.idxs, pa.want);
451
452 /* paranoid */ verify( ret );
453
454 pa.ctx = ctx;
455
456 post( pa.sem );
457 }
458
459 this.pending.empty = true;
460 DONE:;
461 }
462 unlock( this.pending.lock );
463 }
464
465 static void __ioarbiter_notify( $io_context & ctx ) {
466 if(!empty( ctx.arbiter->pending )) {
467 __ioarbiter_notify( *ctx.arbiter, &ctx );
468 }
469 }
470
471 // Simply append to the pending
472 static void __ioarbiter_submit( $io_context * ctx, __u32 idxs[], __u32 have, bool lazy ) {
473 __cfadbg_print_safe(io, "Kernel I/O : submitting %u from the arbiter to context %u\n", have, ctx->fd);
474
475 __cfadbg_print_safe(io, "Kernel I/O : waiting to submit %u\n", have);
476
477 __external_io ei;
478 ei.idxs = idxs;
479 ei.have = have;
480 ei.lazy = lazy;
481
482 block(ctx->ext_sq, (__outstanding_io&)ei);
483
484 __cfadbg_print_safe(io, "Kernel I/O : %u submitted from arbiter\n", have);
485 }
486
487 static void __ioarbiter_flush( $io_context & ctx ) {
488 if(!empty( ctx.ext_sq )) {
489 __STATS__( false, io.flush.external += 1; )
490
491 __cfadbg_print_safe(io, "Kernel I/O : arbiter flushing\n");
492
493 lock( ctx.ext_sq.lock __cfaabi_dbg_ctx2 );
494 {
495 while( !empty(ctx.ext_sq.queue) ) {
496 __external_io & ei = (__external_io&)drop( ctx.ext_sq.queue );
497
498 __submit(&ctx, ei.idxs, ei.have, ei.lazy);
499
500 post( ei.sem );
501 }
502
503 ctx.ext_sq.empty = true;
504 }
505 unlock(ctx.ext_sq.lock );
506 }
507 }
508
509 #if defined(CFA_WITH_IO_URING_IDLE)
510 bool __kernel_read(processor * proc, io_future_t & future, iovec & iov, int fd) {
511 $io_context * ctx = proc->io.ctx;
512 /* paranoid */ verify( ! __preemption_enabled() );
513 /* paranoid */ verify( proc == __cfaabi_tls.this_processor );
514 /* paranoid */ verify( ctx );
515
516 __u32 idx;
517 struct io_uring_sqe * sqe;
518
519 // We can proceed to the fast path
520 if( !__alloc(ctx, &idx, 1) ) return false;
521
522 // Allocation was successful
523 __fill( &sqe, 1, &idx, ctx );
524
525 sqe->user_data = (uintptr_t)&future;
526 sqe->flags = 0;
527 sqe->fd = fd;
528 sqe->off = 0;
529 sqe->ioprio = 0;
530 sqe->fsync_flags = 0;
531 sqe->__pad2[0] = 0;
532 sqe->__pad2[1] = 0;
533 sqe->__pad2[2] = 0;
534
535 #if defined(CFA_HAVE_IORING_OP_READ)
536 sqe->opcode = IORING_OP_READ;
537 sqe->addr = (uint64_t)iov.iov_base;
538 sqe->len = iov.iov_len;
539 #elif defined(CFA_HAVE_READV) && defined(CFA_HAVE_IORING_OP_READV)
540 sqe->opcode = IORING_OP_READV;
541 sqe->addr = (uintptr_t)&iov;
542 sqe->len = 1;
543 #else
544 #error CFA_WITH_IO_URING_IDLE but none of CFA_HAVE_READV, CFA_HAVE_IORING_OP_READV or CFA_HAVE_IORING_OP_READ defined
545 #endif
546
547 asm volatile("": : :"memory");
548
549 /* paranoid */ verify( sqe->user_data == (uintptr_t)&future );
550 __submit( ctx, &idx, 1, true );
551
552 /* paranoid */ verify( proc == __cfaabi_tls.this_processor );
553 /* paranoid */ verify( ! __preemption_enabled() );
554
555 return true;
556 }
557 #endif
558#endif
Note: See TracBrowser for help on using the repository browser.