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io.cfa @ 87e0b015

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Last change on this file since 87e0b015 was 87e0b015, 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: 33.6 KB

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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 __CFA_DEBUG_PRINT_IO__
17	// #define __CFA_DEBUG_PRINT_IO_CORE__
18
19	#include "kernel.hfa"
20
21	#if !defined(HAVE_LINUX_IO_URING_H)
22	void __kernel_io_startup( cluster &, int, bool ) {
23	// Nothing to do without io_uring
24	}
25
26	void __kernel_io_finish_start( cluster & ) {
27	// Nothing to do without io_uring
28	}
29
30	void __kernel_io_prepare_stop( cluster & ) {
31	// Nothing to do without io_uring
32	}
33
34	void __kernel_io_shutdown( cluster &, bool ) {
35	// Nothing to do without io_uring
36	}
37
38	#else
39	extern "C" {
40	#define _GNU_SOURCE /* See feature_test_macros(7) */
41	#include <errno.h>
42	#include <stdint.h>
43	#include <string.h>
44	#include <unistd.h>
45	#include <sys/mman.h>
46	#include <sys/syscall.h>
47
48	#include <linux/io_uring.h>
49	}
50
51	#include "bits/signal.hfa"
52	#include "kernel_private.hfa"
53	#include "thread.hfa"
54
55	uint32_t entries_per_cluster() {
56	return 256;
57	}
58
59	static void * __io_poller_slow( void * arg );
60
61	// Weirdly, some systems that do support io_uring don't actually define these
62	#ifdef __alpha__
63	/*
64	* alpha is the only exception, all other architectures
65	* have common numbers for new system calls.
66	*/
67	#ifndef __NR_io_uring_setup
68	#define __NR_io_uring_setup 535
69	#endif
70	#ifndef __NR_io_uring_enter
71	#define __NR_io_uring_enter 536
72	#endif
73	#ifndef __NR_io_uring_register
74	#define __NR_io_uring_register 537
75	#endif
76	#else /* !__alpha__ */
77	#ifndef __NR_io_uring_setup
78	#define __NR_io_uring_setup 425
79	#endif
80	#ifndef __NR_io_uring_enter
81	#define __NR_io_uring_enter 426
82	#endif
83	#ifndef __NR_io_uring_register
84	#define __NR_io_uring_register 427
85	#endif
86	#endif
87
88	// Fast poller user-thread
89	// Not using the "thread" keyword because we want to control
90	// more carefully when to start/stop it
91	struct __io_poller_fast {
92	struct __io_data * ring;
93	bool waiting;
94	$thread thrd;
95	};
96
97	void ?{}( __io_poller_fast & this, struct cluster & cltr ) {
98	this.ring = cltr.io;
99	this.waiting = true;
100	(this.thrd){ "Fast I/O Poller", cltr };
101	}
102	void ^?{}( __io_poller_fast & mutex this );
103	void main( __io_poller_fast & this );
104	static inline $thread * get_thread( __io_poller_fast & this ) { return &this.thrd; }
105	void ^?{}( __io_poller_fast & mutex this ) {}
106
107	struct __submition_data {
108	// Head and tail of the ring (associated with array)
109	volatile uint32_t * head;
110	volatile uint32_t * tail;
111
112	// The actual kernel ring which uses head/tail
113	// indexes into the sqes arrays
114	uint32_t * array;
115
116	// number of entries and mask to go with it
117	const uint32_t * num;
118	const uint32_t * mask;
119
120	// Submission flags (Not sure what for)
121	uint32_t * flags;
122
123	// number of sqes not submitted (whatever that means)
124	uint32_t * dropped;
125
126	// Like head/tail but not seen by the kernel
127	volatile uint32_t alloc;
128	volatile uint32_t ready;
129
130	__spinlock_t lock;
131
132	// A buffer of sqes (not the actual ring)
133	struct io_uring_sqe * sqes;
134
135	// The location and size of the mmaped area
136	void * ring_ptr;
137	size_t ring_sz;
138
139	// Statistics
140	#if !defined(__CFA_NO_STATISTICS__)
141	struct {
142	struct {
143	volatile unsigned long long int val;
144	volatile unsigned long long int cnt;
145	volatile unsigned long long int block;
146	} submit_avg;
147	} stats;
148	#endif
149	};
150
151	struct __completion_data {
152	// Head and tail of the ring
153	volatile uint32_t * head;
154	volatile uint32_t * tail;
155
156	// number of entries and mask to go with it
157	const uint32_t * mask;
158	const uint32_t * num;
159
160	// number of cqes not submitted (whatever that means)
161	uint32_t * overflow;
162
163	// the kernel ring
164	struct io_uring_cqe * cqes;
165
166	// The location and size of the mmaped area
167	void * ring_ptr;
168	size_t ring_sz;
169
170	// Statistics
171	#if !defined(__CFA_NO_STATISTICS__)
172	struct {
173	struct {
174	unsigned long long int val;
175	unsigned long long int slow_cnt;
176	unsigned long long int fast_cnt;
177	} completed_avg;
178	} stats;
179	#endif
180	};
181
182	struct __io_data {
183	struct __submition_data submit_q;
184	struct __completion_data completion_q;
185	uint32_t ring_flags;
186	int cltr_flags;
187	int fd;
188	semaphore submit;
189	volatile bool done;
190	struct {
191	struct {
192	void * stack;
193	pthread_t kthrd;
194	} slow;
195	__io_poller_fast fast;
196	__bin_sem_t sem;
197	} poller;
198	};
199
200	//=============================================================================================
201	// I/O Startup / Shutdown logic
202	//=============================================================================================
203	void __kernel_io_startup( cluster & this, int io_flags, bool main_cluster ) {
204	this.io = malloc();
205
206	// Step 1 : call to setup
207	struct io_uring_params params;
208	memset(&params, 0, sizeof(params));
209
210	uint32_t nentries = entries_per_cluster();
211
212	int fd = syscall(__NR_io_uring_setup, nentries, &params );
213	if(fd < 0) {
214	abort("KERNEL ERROR: IO_URING SETUP - %s\n", strerror(errno));
215	}
216
217	// Step 2 : mmap result
218	memset( this.io, 0, sizeof(struct __io_data) );
219	struct __submition_data & sq = this.io->submit_q;
220	struct __completion_data & cq = this.io->completion_q;
221
222	// calculate the right ring size
223	sq.ring_sz = params.sq_off.array + (params.sq_entries * sizeof(unsigned) );
224	cq.ring_sz = params.cq_off.cqes + (params.cq_entries * sizeof(struct io_uring_cqe));
225
226	// Requires features
227	#if defined(IORING_FEAT_SINGLE_MMAP)
228	// adjust the size according to the parameters
229	if ((params.features & IORING_FEAT_SINGLE_MMAP) != 0) {
230	cq->ring_sz = sq->ring_sz = max(cq->ring_sz, sq->ring_sz);
231	}
232	#endif
233
234	// mmap the Submit Queue into existence
235	sq.ring_ptr = mmap(0, sq.ring_sz, PROT_READ \| PROT_WRITE, MAP_SHARED \| MAP_POPULATE, fd, IORING_OFF_SQ_RING);
236	if (sq.ring_ptr == (void*)MAP_FAILED) {
237	abort("KERNEL ERROR: IO_URING MMAP1 - %s\n", strerror(errno));
238	}
239
240	// Requires features
241	#if defined(IORING_FEAT_SINGLE_MMAP)
242	// mmap the Completion Queue into existence (may or may not be needed)
243	if ((params.features & IORING_FEAT_SINGLE_MMAP) != 0) {
244	cq->ring_ptr = sq->ring_ptr;
245	}
246	else
247	#endif
248	{
249	// We need multiple call to MMAP
250	cq.ring_ptr = mmap(0, cq.ring_sz, PROT_READ \| PROT_WRITE, MAP_SHARED \| MAP_POPULATE, fd, IORING_OFF_CQ_RING);
251	if (cq.ring_ptr == (void*)MAP_FAILED) {
252	munmap(sq.ring_ptr, sq.ring_sz);
253	abort("KERNEL ERROR: IO_URING MMAP2 - %s\n", strerror(errno));
254	}
255	}
256
257	// mmap the submit queue entries
258	size_t size = params.sq_entries * sizeof(struct io_uring_sqe);
259	sq.sqes = (struct io_uring_sqe *)mmap(0, size, PROT_READ \| PROT_WRITE, MAP_SHARED \| MAP_POPULATE, fd, IORING_OFF_SQES);
260	if (sq.sqes == (struct io_uring_sqe *)MAP_FAILED) {
261	munmap(sq.ring_ptr, sq.ring_sz);
262	if (cq.ring_ptr != sq.ring_ptr) munmap(cq.ring_ptr, cq.ring_sz);
263	abort("KERNEL ERROR: IO_URING MMAP3 - %s\n", strerror(errno));
264	}
265
266	// Get the pointers from the kernel to fill the structure
267	// submit queue
268	sq.head = (volatile uint32_t *)(((intptr_t)sq.ring_ptr) + params.sq_off.head);
269	sq.tail = (volatile uint32_t *)(((intptr_t)sq.ring_ptr) + params.sq_off.tail);
270	sq.mask = ( const uint32_t *)(((intptr_t)sq.ring_ptr) + params.sq_off.ring_mask);
271	sq.num = ( const uint32_t *)(((intptr_t)sq.ring_ptr) + params.sq_off.ring_entries);
272	sq.flags = ( uint32_t *)(((intptr_t)sq.ring_ptr) + params.sq_off.flags);
273	sq.dropped = ( uint32_t *)(((intptr_t)sq.ring_ptr) + params.sq_off.dropped);
274	sq.array = ( uint32_t *)(((intptr_t)sq.ring_ptr) + params.sq_off.array);
275	sq.alloc = *sq.tail;
276	sq.ready = *sq.tail;
277
278	// completion queue
279	cq.head = (volatile uint32_t *)(((intptr_t)cq.ring_ptr) + params.cq_off.head);
280	cq.tail = (volatile uint32_t *)(((intptr_t)cq.ring_ptr) + params.cq_off.tail);
281	cq.mask = ( const uint32_t *)(((intptr_t)cq.ring_ptr) + params.cq_off.ring_mask);
282	cq.num = ( const uint32_t *)(((intptr_t)cq.ring_ptr) + params.cq_off.ring_entries);
283	cq.overflow = ( uint32_t *)(((intptr_t)cq.ring_ptr) + params.cq_off.overflow);
284	cq.cqes = (struct io_uring_cqe *)(((intptr_t)cq.ring_ptr) + params.cq_off.cqes);
285
286	// some paranoid checks
287	/* paranoid / verifyf( (cq.mask) == ((cq.num) - 1ul32), "IO_URING Expected mask to be %u (%u entries), was %u", (cq.num) - 1ul32, cq.num, cq.mask );
288	/* paranoid / verifyf( (cq.num) >= nentries, "IO_URING Expected %u entries, got %u", nentries, *cq.num );
289	/* paranoid / verifyf( (cq.head) == 0, "IO_URING Expected head to be 0, got %u", *cq.head );
290	/* paranoid / verifyf( (cq.tail) == 0, "IO_URING Expected tail to be 0, got %u", *cq.tail );
291
292	/* 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 );
293	/* paranoid / verifyf( (sq.num) >= nentries, "IO_URING Expected %u entries, got %u", nentries, *sq.num );
294	/* paranoid / verifyf( (sq.head) == 0, "IO_URING Expected head to be 0, got %u", *sq.head );
295	/* paranoid / verifyf( (sq.tail) == 0, "IO_URING Expected tail to be 0, got %u", *sq.tail );
296
297	// Update the global ring info
298	this.io->ring_flags = params.flags;
299	this.io->cltr_flags = io_flags;
300	this.io->fd = fd;
301	this.io->done = false;
302	(this.io->submit){ min(sq.num, cq.num) };
303
304	// Initialize statistics
305	#if !defined(__CFA_NO_STATISTICS__)
306	this.io->submit_q.stats.submit_avg.val = 0;
307	this.io->submit_q.stats.submit_avg.cnt = 0;
308	this.io->submit_q.stats.submit_avg.block = 0;
309	this.io->completion_q.stats.completed_avg.val = 0;
310	this.io->completion_q.stats.completed_avg.slow_cnt = 0;
311	this.io->completion_q.stats.completed_avg.fast_cnt = 0;
312	#endif
313
314	if(!main_cluster) {
315	__kernel_io_finish_start( this );
316	}
317	}
318
319	void __kernel_io_finish_start( cluster & this ) {
320	if( this.io->cltr_flags & CFA_CLUSTER_IO_POLLER_USER_THREAD ) {
321	__cfadbg_print_safe(io_core, "Kernel I/O : Creating fast poller for cluter %p\n", &this);
322	(this.io->poller.fast){ this };
323	__thrd_start( this.io->poller.fast, main );
324	}
325
326	// Create the poller thread
327	__cfadbg_print_safe(io_core, "Kernel I/O : Creating slow poller for cluter %p\n", &this);
328	this.io->poller.slow.stack = __create_pthread( &this.io->poller.slow.kthrd, __io_poller_slow, &this );
329	}
330
331	void __kernel_io_prepare_stop( cluster & this ) {
332	__cfadbg_print_safe(io_core, "Kernel I/O : Stopping pollers for cluster\n", &this);
333	// Notify the poller thread of the shutdown
334	__atomic_store_n(&this.io->done, true, __ATOMIC_SEQ_CST);
335
336	// Stop the IO Poller
337	sigval val = { 1 };
338	pthread_sigqueue( this.io->poller.slow.kthrd, SIGUSR1, val );
339	post( this.io->poller.sem );
340
341	// Wait for the poller thread to finish
342	pthread_join( this.io->poller.slow.kthrd, 0p );
343	free( this.io->poller.slow.stack );
344
345	__cfadbg_print_safe(io_core, "Kernel I/O : Slow poller stopped for cluster\n", &this);
346
347	if( this.io->cltr_flags & CFA_CLUSTER_IO_POLLER_USER_THREAD ) {
348	with( this.io->poller.fast ) {
349	/* paranoid */ verify( waiting ); // The thread shouldn't be in a system call
350	/* paranoid */ verify( this.procs.head == 0p \|\| &this == mainCluster );
351	/* paranoid */ verify( this.idles.head == 0p \|\| &this == mainCluster );
352
353	// We need to adjust the clean-up based on where the thread is
354	if( thrd.preempted != __NO_PREEMPTION ) {
355
356	// This is the tricky case
357	// The thread was preempted and now it is on the ready queue
358	/* paranoid */ verify( thrd.state == Active ); // The thread better be in this state
359	/* paranoid */ verify( thrd.next == 1p ); // The thread should be the last on the list
360	/* paranoid */ verify( this.ready_queue.head == &thrd ); // The thread should be the only thing on the list
361
362	// Remove the thread from the ready queue of this cluster
363	this.ready_queue.head = 1p;
364	thrd.next = 0p;
365
366	// Fixup the thread state
367	thrd.state = Blocked;
368	thrd.preempted = __NO_PREEMPTION;
369
370	// Pretend like the thread was blocked all along
371	}
372	// !!! This is not an else if !!!
373	if( thrd.state == Blocked ) {
374
375	// This is the "easy case"
376	// The thread is parked and can easily be moved to active cluster
377	verify( thrd.curr_cluster != active_cluster() \|\| thrd.curr_cluster == mainCluster );
378	thrd.curr_cluster = active_cluster();
379
380	// unpark the fast io_poller
381	unpark( &thrd __cfaabi_dbg_ctx2 );
382	}
383	else {
384
385	// The thread is in a weird state
386	// I don't know what to do here
387	abort("Fast poller thread is in unexpected state, cannot clean-up correctly\n");
388	}
389
390	}
391
392	^(this.io->poller.fast){};
393
394	__cfadbg_print_safe(io_core, "Kernel I/O : Fast poller stopped for cluster\n", &this);
395	}
396	}
397
398	void __kernel_io_shutdown( cluster & this, bool main_cluster ) {
399	if(!main_cluster) {
400	__kernel_io_prepare_stop( this );
401	}
402
403	// print statistics
404	#if !defined(__CFA_NO_STATISTICS__)
405	if(this.print_stats) {
406	with(this.io->submit_q.stats, this.io->completion_q.stats) {
407	__cfaabi_bits_print_safe( STDERR_FILENO,
408	"----- I/O uRing Stats -----\n"
409	"- total submit calls : %'15llu\n"
410	"- avg submit : %'18.2lf\n"
411	"- pre-submit block %% : %'18.2lf\n"
412	"- total wait calls : %'15llu (%'llu slow, %'llu fast)\n"
413	"- avg completion/wait : %'18.2lf\n",
414	submit_avg.cnt,
415	((double)submit_avg.val) / submit_avg.cnt,
416	(100.0 * submit_avg.block) / submit_avg.cnt,
417	completed_avg.slow_cnt + completed_avg.fast_cnt,
418	completed_avg.slow_cnt, completed_avg.fast_cnt,
419	((double)completed_avg.val) / (completed_avg.slow_cnt + completed_avg.fast_cnt)
420	);
421	}
422	}
423	#endif
424
425	// Shutdown the io rings
426	struct __submition_data & sq = this.io->submit_q;
427	struct __completion_data & cq = this.io->completion_q;
428
429	// unmap the submit queue entries
430	munmap(sq.sqes, (sq.num) sizeof(struct io_uring_sqe));
431
432	// unmap the Submit Queue ring
433	munmap(sq.ring_ptr, sq.ring_sz);
434
435	// unmap the Completion Queue ring, if it is different
436	if (cq.ring_ptr != sq.ring_ptr) {
437	munmap(cq.ring_ptr, cq.ring_sz);
438	}
439
440	// close the file descriptor
441	close(this.io->fd);
442
443	free( this.io );
444	}
445
446	//=============================================================================================
447	// I/O Polling
448	//=============================================================================================
449	struct io_user_data {
450	int32_t result;
451	$thread * thrd;
452	};
453
454	// Process a single completion message from the io_uring
455	// This is NOT thread-safe
456	static int __drain_io( struct __io_data & ring, sigset_t * mask, int waitcnt, bool in_kernel ) {
457	int ret = syscall( __NR_io_uring_enter, ring.fd, 0, waitcnt, IORING_ENTER_GETEVENTS, mask, _NSIG / 8);
458	if( ret < 0 ) {
459	switch((int)errno) {
460	case EAGAIN:
461	case EINTR:
462	return -EAGAIN;
463	default:
464	abort( "KERNEL ERROR: IO_URING WAIT - %s\n", strerror(errno) );
465	}
466	}
467
468	// Drain the queue
469	unsigned head = *ring.completion_q.head;
470	unsigned tail = __atomic_load_n(ring.completion_q.tail, __ATOMIC_ACQUIRE);
471
472	// Nothing was new return 0
473	if (head == tail) {
474	return 0;
475	}
476
477	uint32_t count = tail - head;
478	for(i; count) {
479	unsigned idx = (head + i) & (*ring.completion_q.mask);
480	struct io_uring_cqe & cqe = ring.completion_q.cqes[idx];
481
482	/* paranoid */ verify(&cqe);
483
484	struct io_user_data * data = (struct io_user_data *)cqe.user_data;
485	__cfadbg_print_safe( io, "Kernel I/O : Performed reading io cqe %p, result %d for %p\n", data, cqe.res, data->thrd );
486
487	data->result = cqe.res;
488	if(!in_kernel) { unpark( data->thrd __cfaabi_dbg_ctx2 ); }
489	else { __unpark( data->thrd __cfaabi_dbg_ctx2 ); }
490	}
491
492	// Allow new submissions to happen
493	V(ring.submit, count);
494
495	// Mark to the kernel that the cqe has been seen
496	// Ensure that the kernel only sees the new value of the head index after the CQEs have been read.
497	__atomic_fetch_add( ring.completion_q.head, count, __ATOMIC_RELAXED );
498
499	return count;
500	}
501
502	static void * __io_poller_slow( void * arg ) {
503	cluster * cltr = (cluster *)arg;
504	struct __io_data & ring = *cltr->io;
505
506	sigset_t mask;
507	sigfillset(&mask);
508	if ( pthread_sigmask( SIG_BLOCK, &mask, 0p ) == -1 ) {
509	abort( "KERNEL ERROR: IO_URING - pthread_sigmask" );
510	}
511
512	sigdelset( &mask, SIGUSR1 );
513
514	verify( (ring.submit_q.head) == (ring.submit_q.tail) );
515	verify( (ring.completion_q.head) == (ring.completion_q.tail) );
516
517	__cfadbg_print_safe(io_core, "Kernel I/O : Slow poller for ring %p ready\n", &ring);
518
519	if( ring.cltr_flags & CFA_CLUSTER_IO_POLLER_USER_THREAD ) {
520	while(!__atomic_load_n(&ring.done, __ATOMIC_SEQ_CST)) {
521	// In the user-thread approach drain and if anything was drained,
522	// batton pass to the user-thread
523	int count = __drain_io( ring, &mask, 1, true );
524
525	// Update statistics
526	#if !defined(__CFA_NO_STATISTICS__)
527	ring.completion_q.stats.completed_avg.val += count;
528	ring.completion_q.stats.completed_avg.slow_cnt += 1;
529	#endif
530
531	if(count > 0) {
532	__cfadbg_print_safe(io_core, "Kernel I/O : Moving to ring %p to fast poller\n", &ring);
533	__unpark( &ring.poller.fast.thrd __cfaabi_dbg_ctx2 );
534	wait( ring.poller.sem );
535	}
536	}
537	}
538	else {
539	while(!__atomic_load_n(&ring.done, __ATOMIC_SEQ_CST)) {
540	//In the naive approach, just poll the io completion queue directly
541	int count = __drain_io( ring, &mask, 1, true );
542
543	// Update statistics
544	#if !defined(__CFA_NO_STATISTICS__)
545	ring.completion_q.stats.completed_avg.val += count;
546	ring.completion_q.stats.completed_avg.slow_cnt += 1;
547	#endif
548	}
549	}
550
551	__cfadbg_print_safe(io_core, "Kernel I/O : Slow poller for ring %p stopping\n", &ring);
552
553	return 0p;
554	}
555
556	void main( __io_poller_fast & this ) {
557	verify( this.ring->cltr_flags & CFA_CLUSTER_IO_POLLER_USER_THREAD );
558
559	// Start parked
560	park( __cfaabi_dbg_ctx );
561
562	__cfadbg_print_safe(io_core, "Kernel I/O : Fast poller for ring %p ready\n", &this.ring);
563
564	int reset = 0;
565
566	// Then loop until we need to start
567	while(!__atomic_load_n(&this.ring->done, __ATOMIC_SEQ_CST)) {
568	// Drain the io
569	this.waiting = false;
570	int count = __drain_io( *this.ring, 0p, 0, false );
571	reset += count > 0 ? 1 : 0;
572
573	// Update statistics
574	#if !defined(__CFA_NO_STATISTICS__)
575	this.ring->completion_q.stats.completed_avg.val += count;
576	this.ring->completion_q.stats.completed_avg.fast_cnt += 1;
577	#endif
578
579	this.waiting = true;
580	if(reset < 5) {
581	// If we got something, just yield and check again
582	yield();
583	}
584	else {
585	// We didn't get anything baton pass to the slow poller
586	__cfadbg_print_safe(io_core, "Kernel I/O : Moving to ring %p to slow poller\n", &this.ring);
587	post( this.ring->poller.sem );
588	park( __cfaabi_dbg_ctx );
589	reset = 0;
590	}
591	}
592
593	__cfadbg_print_safe(io_core, "Kernel I/O : Fast poller for ring %p stopping\n", &this.ring);
594	}
595
596	//=============================================================================================
597	// I/O Submissions
598	//=============================================================================================
599
600	// Submition steps :
601	// 1 - We need to make sure we don't overflow any of the buffer, P(ring.submit) to make sure
602	// entries are available. The semaphore make sure that there is no more operations in
603	// progress then the number of entries in the buffer. This probably limits concurrency
604	// more than necessary since submitted but not completed operations don't need any
605	// entries in user space. However, I don't know what happens if we overflow the buffers
606	// because too many requests completed at once. This is a safe approach in all cases.
607	// Furthermore, with hundreds of entries, this may be okay.
608	//
609	// 2 - Allocate a queue entry. The ring already has memory for all entries but only the ones
610	// listed in sq.array are visible by the kernel. For those not listed, the kernel does not
611	// offer any assurance that an entry is not being filled by multiple flags. Therefore, we
612	// need to write an allocator that allows allocating concurrently.
613	//
614	// 3 - Actually fill the submit entry, this is the only simple and straightforward step.
615	//
616	// 4 - Append the entry index to the array and adjust the tail accordingly. This operation
617	// needs to arrive to two concensus at the same time:
618	// A - The order in which entries are listed in the array: no two threads must pick the
619	// same index for their entries
620	// B - When can the tail be update for the kernel. EVERY entries in the array between
621	// head and tail must be fully filled and shouldn't ever be touched again.
622	//
623
624	static inline [* struct io_uring_sqe, uint32_t] __submit_alloc( struct __io_data & ring ) {
625	// Wait for a spot to be available
626	__attribute__((unused)) bool blocked = P(ring.submit);
627	#if !defined(__CFA_NO_STATISTICS__)
628	__atomic_fetch_add( &ring.submit_q.stats.submit_avg.block, blocked ? 1ul64 : 0ul64, __ATOMIC_RELAXED );
629	#endif
630
631	// Allocate the sqe
632	uint32_t idx = __atomic_fetch_add(&ring.submit_q.alloc, 1ul32, __ATOMIC_SEQ_CST);
633
634	// Validate that we didn't overflow anything
635	// Check that nothing overflowed
636	/* paranoid */ verify( true );
637
638	// Check that it goes head -> tail -> alloc and never head -> alloc -> tail
639	/* paranoid */ verify( true );
640
641	// Return the sqe
642	return [&ring.submit_q.sqes[ idx & (*ring.submit_q.mask)], idx];
643	}
644
645	static inline void __submit( struct __io_data & ring, uint32_t idx ) {
646	// get mutual exclusion
647	lock(ring.submit_q.lock __cfaabi_dbg_ctx2);
648
649	// Append to the list of ready entries
650	uint32_t * tail = ring.submit_q.tail;
651	const uint32_t mask = *ring.submit_q.mask;
652
653	ring.submit_q.array[ (*tail) & mask ] = idx & mask;
654	__atomic_fetch_add(tail, 1ul32, __ATOMIC_SEQ_CST);
655
656	// Submit however, many entries need to be submitted
657	int ret = syscall( __NR_io_uring_enter, ring.fd, 1, 0, 0, 0p, 0);
658	if( ret < 0 ) {
659	switch((int)errno) {
660	default:
661	abort( "KERNEL ERROR: IO_URING SUBMIT - %s\n", strerror(errno) );
662	}
663	}
664
665	// update statistics
666	#if !defined(__CFA_NO_STATISTICS__)
667	ring.submit_q.stats.submit_avg.val += 1;
668	ring.submit_q.stats.submit_avg.cnt += 1;
669	#endif
670
671	unlock(ring.submit_q.lock);
672	// Make sure that idx was submitted
673	// Be careful to not get false positive if we cycled the entire list or that someone else submitted for us
674	__cfadbg_print_safe( io, "Kernel I/O : Performed io_submit for %p, returned %d\n", active_thread(), ret );
675	}
676
677	static inline void ?{}(struct io_uring_sqe & this, uint8_t opcode, int fd) {
678	this.opcode = opcode;
679	#if !defined(IOSQE_ASYNC)
680	this.flags = 0;
681	#else
682	this.flags = IOSQE_ASYNC;
683	#endif
684	this.ioprio = 0;
685	this.fd = fd;
686	this.off = 0;
687	this.addr = 0;
688	this.len = 0;
689	this.rw_flags = 0;
690	this.__pad2[0] = this.__pad2[1] = this.__pad2[2] = 0;
691	}
692
693	static inline void ?{}(struct io_uring_sqe & this, uint8_t opcode, int fd, void * addr, uint32_t len, uint64_t off ) {
694	(this){ opcode, fd };
695	this.off = off;
696	this.addr = (uint64_t)addr;
697	this.len = len;
698	}
699
700
701	//=============================================================================================
702	// I/O Interface
703	//=============================================================================================
704
705	#define __submit_prelude \
706	struct __io_data & ring = *active_cluster()->io; \
707	struct io_uring_sqe * sqe; \
708	uint32_t idx; \
709	[sqe, idx] = __submit_alloc( ring );
710
711	#define __submit_wait \
712	io_user_data data = { 0, active_thread() }; \
713	/__cfaabi_bits_print_safe( STDERR_FILENO, "Preparing user data %p for %p\n", &data, data.thrd );/ \
714	sqe->user_data = (uint64_t)&data; \
715	__submit( ring, idx ); \
716	park( __cfaabi_dbg_ctx ); \
717	return data.result;
718	#endif
719
720	// Some forward declarations
721	extern "C" {
722	#include <unistd.h>
723	#include <sys/types.h>
724	#include <sys/socket.h>
725	#include <sys/syscall.h>
726
727	#if defined(HAVE_PREADV2)
728	struct iovec;
729	extern ssize_t preadv2 (int fd, const struct iovec *iov, int iovcnt, off_t offset, int flags);
730	#endif
731	#if defined(HAVE_PWRITEV2)
732	struct iovec;
733	extern ssize_t pwritev2(int fd, const struct iovec *iov, int iovcnt, off_t offset, int flags);
734	#endif
735
736	extern int fsync(int fd);
737	extern int sync_file_range(int fd, int64_t offset, int64_t nbytes, unsigned int flags);
738
739	struct msghdr;
740	struct sockaddr;
741	extern ssize_t sendmsg(int sockfd, const struct msghdr *msg, int flags);
742	extern ssize_t recvmsg(int sockfd, struct msghdr *msg, int flags);
743	extern ssize_t send(int sockfd, const void *buf, size_t len, int flags);
744	extern ssize_t recv(int sockfd, void *buf, size_t len, int flags);
745	extern int accept4(int sockfd, struct sockaddr addr, socklen_t addrlen, int flags);
746	extern int connect(int sockfd, const struct sockaddr *addr, socklen_t addrlen);
747
748	extern int fallocate(int fd, int mode, uint64_t offset, uint64_t len);
749	extern int posix_fadvise(int fd, uint64_t offset, uint64_t len, int advice);
750	extern int madvise(void *addr, size_t length, int advice);
751
752	extern int openat(int dirfd, const char *pathname, int flags, mode_t mode);
753	extern int close(int fd);
754
755	extern ssize_t read (int fd, void *buf, size_t count);
756	}
757
758	//-----------------------------------------------------------------------------
759	// Asynchronous operations
760	#if defined(HAVE_PREADV2)
761	ssize_t cfa_preadv2(int fd, const struct iovec *iov, int iovcnt, off_t offset, int flags) {
762	#if !defined(HAVE_LINUX_IO_URING_H) \|\| !defined(IORING_OP_READV)
763	return preadv2(fd, iov, iovcnt, offset, flags);
764	#else
765	__submit_prelude
766
767	(*sqe){ IORING_OP_READV, fd, iov, iovcnt, offset };
768
769	__submit_wait
770	#endif
771	}
772	#endif
773
774	#if defined(HAVE_PWRITEV2)
775	ssize_t cfa_pwritev2(int fd, const struct iovec *iov, int iovcnt, off_t offset, int flags) {
776	#if !defined(HAVE_LINUX_IO_URING_H) \|\| !defined(IORING_OP_WRITEV)
777	return pwritev2(fd, iov, iovcnt, offset, flags);
778	#else
779	__submit_prelude
780
781	(*sqe){ IORING_OP_WRITEV, fd, iov, iovcnt, offset };
782
783	__submit_wait
784	#endif
785	}
786	#endif
787
788	int cfa_fsync(int fd) {
789	#if !defined(HAVE_LINUX_IO_URING_H) \|\| !defined(IORING_OP_FSYNC)
790	return fsync(fd);
791	#else
792	__submit_prelude
793
794	(*sqe){ IORING_OP_FSYNC, fd };
795
796	__submit_wait
797	#endif
798	}
799
800	int cfa_sync_file_range(int fd, int64_t offset, int64_t nbytes, unsigned int flags) {
801	#if !defined(HAVE_LINUX_IO_URING_H) \|\| !defined(IORING_OP_SYNC_FILE_RANGE)
802	return sync_file_range(fd, offset, nbytes, flags);
803	#else
804	__submit_prelude
805
806	(*sqe){ IORING_OP_SYNC_FILE_RANGE, fd };
807	sqe->off = offset;
808	sqe->len = nbytes;
809	sqe->sync_range_flags = flags;
810
811	__submit_wait
812	#endif
813	}
814
815
816	ssize_t cfa_sendmsg(int sockfd, const struct msghdr *msg, int flags) {
817	#if !defined(HAVE_LINUX_IO_URING_H) \|\| !defined(IORING_OP_SENDMSG)
818	return sendmsg(sockfd, msg, flags);
819	#else
820	__submit_prelude
821
822	(*sqe){ IORING_OP_SENDMSG, sockfd, msg, 1, 0 };
823	sqe->msg_flags = flags;
824
825	__submit_wait
826	#endif
827	}
828
829	ssize_t cfa_recvmsg(int sockfd, struct msghdr *msg, int flags) {
830	#if !defined(HAVE_LINUX_IO_URING_H) \|\| !defined(IORING_OP_RECVMSG)
831	return recvmsg(sockfd, msg, flags);
832	#else
833	__submit_prelude
834
835	(*sqe){ IORING_OP_RECVMSG, sockfd, msg, 1, 0 };
836	sqe->msg_flags = flags;
837
838	__submit_wait
839	#endif
840	}
841
842	ssize_t cfa_send(int sockfd, const void *buf, size_t len, int flags) {
843	#if !defined(HAVE_LINUX_IO_URING_H) \|\| !defined(IORING_OP_SEND)
844	return send( sockfd, buf, len, flags );
845	#else
846	__submit_prelude
847
848	(*sqe){ IORING_OP_SEND, sockfd };
849	sqe->addr = (uint64_t)buf;
850	sqe->len = len;
851	sqe->msg_flags = flags;
852
853	__submit_wait
854	#endif
855	}
856
857	ssize_t cfa_recv(int sockfd, void *buf, size_t len, int flags) {
858	#if !defined(HAVE_LINUX_IO_URING_H) \|\| !defined(IORING_OP_RECV)
859	return recv( sockfd, buf, len, flags );
860	#else
861	__submit_prelude
862
863	(*sqe){ IORING_OP_RECV, sockfd };
864	sqe->addr = (uint64_t)buf;
865	sqe->len = len;
866	sqe->msg_flags = flags;
867
868	__submit_wait
869	#endif
870	}
871
872	int cfa_accept4(int sockfd, struct sockaddr addr, socklen_t addrlen, int flags) {
873	#if !defined(HAVE_LINUX_IO_URING_H) \|\| !defined(IORING_OP_ACCEPT)
874	return accept4( sockfd, addr, addrlen, flags );
875	#else
876	__submit_prelude
877
878	(*sqe){ IORING_OP_ACCEPT, sockfd };
879	sqe->addr = addr;
880	sqe->addr2 = addrlen;
881	sqe->accept_flags = flags;
882
883	__submit_wait
884	#endif
885	}
886
887	int cfa_connect(int sockfd, const struct sockaddr *addr, socklen_t addrlen) {
888	#if !defined(HAVE_LINUX_IO_URING_H) \|\| !defined(IORING_OP_CONNECT)
889	return connect( sockfd, addr, addrlen );
890	#else
891	__submit_prelude
892
893	(*sqe){ IORING_OP_CONNECT, sockfd };
894	sqe->addr = (uint64_t)addr;
895	sqe->off = addrlen;
896
897	__submit_wait
898	#endif
899	}
900
901	int cfa_fallocate(int fd, int mode, uint64_t offset, uint64_t len) {
902	#if !defined(HAVE_LINUX_IO_URING_H) \|\| !defined(IORING_OP_FALLOCATE)
903	return fallocate( fd, mode, offset, len );
904	#else
905	__submit_prelude
906
907	(*sqe){ IORING_OP_FALLOCATE, fd };
908	sqe->off = offset;
909	sqe->len = length;
910	sqe->mode = mode;
911
912	__submit_wait
913	#endif
914	}
915
916	int cfa_fadvise(int fd, uint64_t offset, uint64_t len, int advice) {
917	#if !defined(HAVE_LINUX_IO_URING_H) \|\| !defined(IORING_OP_FADVISE)
918	return posix_fadvise( fd, offset, len, advice );
919	#else
920	__submit_prelude
921
922	(*sqe){ IORING_OP_FADVISE, fd };
923	sqe->off = (uint64_t)offset;
924	sqe->len = length;
925	sqe->fadvise_advice = advice;
926
927	__submit_wait
928	#endif
929	}
930
931	int cfa_madvise(void *addr, size_t length, int advice) {
932	#if !defined(HAVE_LINUX_IO_URING_H) \|\| !defined(IORING_OP_MADVISE)
933	return madvise( addr, length, advice );
934	#else
935	__submit_prelude
936
937	(*sqe){ IORING_OP_MADVISE, 0 };
938	sqe->addr = (uint64_t)addr;
939	sqe->len = length;
940	sqe->fadvise_advice = advice;
941
942	__submit_wait
943	#endif
944	}
945
946	int cfa_openat(int dirfd, const char *pathname, int flags, mode_t mode) {
947	#if !defined(HAVE_LINUX_IO_URING_H) \|\| !defined(IORING_OP_OPENAT)
948	return openat( dirfd, pathname, flags, mode );
949	#else
950	__submit_prelude
951
952	(*sqe){ IORING_OP_OPENAT, dirfd };
953	sqe->addr = (uint64_t)pathname;
954	sqe->open_flags = flags;
955	sqe->mode = mode;
956
957	__submit_wait
958	#endif
959	}
960
961	int cfa_close(int fd) {
962	#if !defined(HAVE_LINUX_IO_URING_H) \|\| !defined(IORING_OP_CLOSE)
963	return close( fd );
964	#else
965	__submit_prelude
966
967	(*sqe){ IORING_OP_CLOSE, fd };
968
969	__submit_wait
970	#endif
971	}
972
973
974	ssize_t cfa_read(int fd, void *buf, size_t count) {
975	#if !defined(HAVE_LINUX_IO_URING_H) \|\| !defined(IORING_OP_READ)
976	return read( fd, buf, count );
977	#else
978	__submit_prelude
979
980	(*sqe){ IORING_OP_READ, fd, buf, count, 0 };
981
982	__submit_wait
983	#endif
984	}
985
986	ssize_t cfa_write(int fd, void *buf, size_t count) {
987	#if !defined(HAVE_LINUX_IO_URING_H) \|\| !defined(IORING_OP_WRITE)
988	return read( fd, buf, count );
989	#else
990	__submit_prelude
991
992	(*sqe){ IORING_OP_WRITE, fd, buf, count, 0 };
993
994	__submit_wait
995	#endif
996	}
997
998	//-----------------------------------------------------------------------------
999	// Check if a function is asynchronous
1000
1001	// Macro magic to reduce the size of the following switch case
1002	#define IS_DEFINED_APPLY(f, ...) f(__VA_ARGS__)
1003	#define IS_DEFINED_SECOND(first, second, ...) second
1004	#define IS_DEFINED_TEST(expansion) _CFA_IO_FEATURE_##expansion
1005	#define IS_DEFINED(macro) IS_DEFINED_APPLY( IS_DEFINED_SECOND,IS_DEFINED_TEST(macro) false, true)
1006
1007	bool has_user_level_blocking( fptr_t func ) {
1008	#if defined(HAVE_LINUX_IO_URING_H)
1009	#if defined(HAVE_PREADV2)
1010	if( /func == (fptr_t)preadv2 \|\| /
1011	func == (fptr_t)cfa_preadv2 )
1012	#define _CFA_IO_FEATURE_IORING_OP_READV ,
1013	return IS_DEFINED(IORING_OP_READV);
1014	#endif
1015
1016	#if defined(HAVE_PWRITEV2)
1017	if( /func == (fptr_t)pwritev2 \|\| /
1018	func == (fptr_t)cfa_pwritev2 )
1019	#define _CFA_IO_FEATURE_IORING_OP_WRITEV ,
1020	return IS_DEFINED(IORING_OP_WRITEV);
1021	#endif
1022
1023	if( /func == (fptr_t)fsync \|\| /
1024	func == (fptr_t)cfa_fsync )
1025	#define _CFA_IO_FEATURE_IORING_OP_FSYNC ,
1026	return IS_DEFINED(IORING_OP_FSYNC);
1027
1028	if( /func == (fptr_t)ync_file_range \|\| /
1029	func == (fptr_t)cfa_sync_file_range )
1030	#define _CFA_IO_FEATURE_IORING_OP_SYNC_FILE_RANGE ,
1031	return IS_DEFINED(IORING_OP_SYNC_FILE_RANGE);
1032
1033	if( /func == (fptr_t)sendmsg \|\| /
1034	func == (fptr_t)cfa_sendmsg )
1035	#define _CFA_IO_FEATURE_IORING_OP_SENDMSG ,
1036	return IS_DEFINED(IORING_OP_SENDMSG);
1037
1038	if( /func == (fptr_t)recvmsg \|\| /
1039	func == (fptr_t)cfa_recvmsg )
1040	#define _CFA_IO_FEATURE_IORING_OP_RECVMSG ,
1041	return IS_DEFINED(IORING_OP_RECVMSG);
1042
1043	if( /func == (fptr_t)send \|\| /
1044	func == (fptr_t)cfa_send )
1045	#define _CFA_IO_FEATURE_IORING_OP_SEND ,
1046	return IS_DEFINED(IORING_OP_SEND);
1047
1048	if( /func == (fptr_t)recv \|\| /
1049	func == (fptr_t)cfa_recv )
1050	#define _CFA_IO_FEATURE_IORING_OP_RECV ,
1051	return IS_DEFINED(IORING_OP_RECV);
1052
1053	if( /func == (fptr_t)accept4 \|\| /
1054	func == (fptr_t)cfa_accept4 )
1055	#define _CFA_IO_FEATURE_IORING_OP_ACCEPT ,
1056	return IS_DEFINED(IORING_OP_ACCEPT);
1057
1058	if( /func == (fptr_t)connect \|\| /
1059	func == (fptr_t)cfa_connect )
1060	#define _CFA_IO_FEATURE_IORING_OP_CONNECT ,
1061	return IS_DEFINED(IORING_OP_CONNECT);
1062
1063	if( /func == (fptr_t)fallocate \|\| /
1064	func == (fptr_t)cfa_fallocate )
1065	#define _CFA_IO_FEATURE_IORING_OP_FALLOCATE ,
1066	return IS_DEFINED(IORING_OP_FALLOCATE);
1067
1068	if( /func == (fptr_t)posix_fadvise \|\| /
1069	func == (fptr_t)cfa_fadvise )
1070	#define _CFA_IO_FEATURE_IORING_OP_FADVISE ,
1071	return IS_DEFINED(IORING_OP_FADVISE);
1072
1073	if( /func == (fptr_t)madvise \|\| /
1074	func == (fptr_t)cfa_madvise )
1075	#define _CFA_IO_FEATURE_IORING_OP_MADVISE ,
1076	return IS_DEFINED(IORING_OP_MADVISE);
1077
1078	if( /func == (fptr_t)openat \|\| /
1079	func == (fptr_t)cfa_openat )
1080	#define _CFA_IO_FEATURE_IORING_OP_OPENAT ,
1081	return IS_DEFINED(IORING_OP_OPENAT);
1082
1083	if( /func == (fptr_t)close \|\| /
1084	func == (fptr_t)cfa_close )
1085	#define _CFA_IO_FEATURE_IORING_OP_CLOSE ,
1086	return IS_DEFINED(IORING_OP_CLOSE);
1087
1088	if( /func == (fptr_t)read \|\| /
1089	func == (fptr_t)cfa_read )
1090	#define _CFA_IO_FEATURE_IORING_OP_READ ,
1091	return IS_DEFINED(IORING_OP_READ);
1092
1093	if( /func == (fptr_t)write \|\| /
1094	func == (fptr_t)cfa_write )
1095	#define _CFA_IO_FEATURE_IORING_OP_WRITE ,
1096	return IS_DEFINED(IORING_OP_WRITE);
1097	#endif
1098
1099	return false;
1100	}

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