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io.cfa@ 708ae38

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ADT ast-experimental enum pthread-emulation qualifiedEnum

Last change on this file since 708ae38 was 708ae38, checked in by Thierry Delisle <tdelisle@…>, 4 years ago
Some more cleanup and grow/shrink now readjusts io timestamps. (They are still unused).
Property mode set to `100644`
File size: 17.4 KB

Rev	Line
[ecf6b46]	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
[3e2b9c9]	16	#define __cforall_thread__
[43784ac]	17	#define _GNU_SOURCE
[3e2b9c9]	18
[20ab637]	19	#if defined(__CFA_DEBUG__)
[d60d30e]	20	// #define __CFA_DEBUG_PRINT_IO__
	21	// #define __CFA_DEBUG_PRINT_IO_CORE__
[20ab637]	22	#endif
[4069faad]	23
[f6660520]	24
[3e2b9c9]	25	#if defined(CFA_HAVE_LINUX_IO_URING_H)
[31bb2e1]	26	#include <errno.h>
[3e2b9c9]	27	#include <signal.h>
[31bb2e1]	28	#include <stdint.h>
	29	#include <string.h>
	30	#include <unistd.h>
	31
[92976d9]	32	extern "C" {
	33	#include <sys/syscall.h>
[dddb3dd0]	34	#include <sys/eventfd.h>
[d3605f8]	35	#include <sys/uio.h>
[92976d9]	36
	37	#include <linux/io_uring.h>
	38	}
	39
[3e2b9c9]	40	#include "stats.hfa"
	41	#include "kernel.hfa"
	42	#include "kernel/fwd.hfa"
[708ae38]	43	#include "kernel/private.hfa"
[3e2b9c9]	44	#include "io/types.hfa"
[185efe6]	45
[2fab24e3]	46	__attribute__((unused)) static const char * opcodes[] = {
[426f60c]	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
[11054eb]	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 & );
[dddb3dd0]	87	static inline void __ioarbiter_notify( $io_context & ctx );
[92976d9]	88	//=============================================================================================
	89	// I/O Polling
	90	//=============================================================================================
[78da4ab]	91	static inline unsigned __flush( struct $io_context & );
	92	static inline __u32 __release_sqes( struct $io_context & );
[24e321c]	93	extern void __kernel_unpark( thread$ * thrd, unpark_hint );
[1d5e4711]	94
[c1c95b1]	95	bool __cfa_io_drain( processor * proc ) {
[dddb3dd0]	96	/* paranoid */ verify( ! __preemption_enabled() );
[e9c0b4c]	97	/* paranoid */ verify( ready_schedule_islocked() );
[dddb3dd0]	98	/* paranoid */ verify( proc );
	99	/* paranoid */ verify( proc->io.ctx );
[6f121b8]	100
[d384787]	101	// Drain the queue
[dddb3dd0]	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;
[92976d9]	106
[4998155]	107	__u32 count = tail - head;
[dddb3dd0]	108	__STATS__( false, io.calls.drain++; io.calls.completed += count; )
[d60d30e]	109
[c1c95b1]	110	if(count == 0) return false;
	111
[d384787]	112	for(i; count) {
[6f121b8]	113	unsigned idx = (head + i) & mask;
[dddb3dd0]	114	volatile struct io_uring_cqe & cqe = ctx->cq.cqes[idx];
[92976d9]	115
[d384787]	116	/* paranoid */ verify(&cqe);
[92976d9]	117
[78da4ab]	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
[24e321c]	121	__kernel_unpark( fulfil( *future, cqe.res, false ), UNPARK_LOCAL );
[78da4ab]	122	}
	123
[dddb3dd0]	124	__cfadbg_print_safe(io, "Kernel I/O : %u completed\n", count);
[2d8f7b0]	125
[92976d9]	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.
[dddb3dd0]	128	__atomic_store_n( ctx->cq.head, head + count, __ATOMIC_SEQ_CST );
[92976d9]	129
[e9c0b4c]	130	/* paranoid */ verify( ready_schedule_islocked() );
[dddb3dd0]	131	/* paranoid */ verify( ! __preemption_enabled() );
	132
[c1c95b1]	133	return true;
[92976d9]	134	}
	135
[c7b2215]	136	bool __cfa_io_flush( processor * proc, int min_comp ) {
[dddb3dd0]	137	/* paranoid */ verify( ! __preemption_enabled() );
	138	/* paranoid */ verify( proc );
	139	/* paranoid */ verify( proc->io.ctx );
[1539bbd]	140
[d36bac7]	141	__attribute__((unused)) cluster * cltr = proc->cltr;
[dddb3dd0]	142	$io_context & ctx = *proc->io.ctx;
[78da4ab]	143
[11054eb]	144	__ioarbiter_flush( ctx );
[3c039b0]	145
[21a5bfb7]	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	}
[61dd73d]	161	}
[ece0e80]	162
[21a5bfb7]	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 );
[dddb3dd0]	167
[21a5bfb7]	168	ctx.sq.to_submit -= ret;
[ece0e80]	169
[21a5bfb7]	170	/* paranoid / verify( ctx.sq.to_submit <= ctx.sq.num );
[5dadc9b7]	171
[21a5bfb7]	172	// Release the consumed SQEs
	173	__release_sqes( ctx );
[ece0e80]	174
[21a5bfb7]	175	/* paranoid */ verify( ! __preemption_enabled() );
	176
[d529ad0]	177	__atomic_store_n(&ctx.proc->io.pending, false, __ATOMIC_RELAXED);
[21a5bfb7]	178	}
[61dd73d]	179
[7ef162b2]	180	ready_schedule_lock();
	181	bool ret = __cfa_io_drain( proc );
	182	ready_schedule_unlock();
	183	return ret;
[61dd73d]	184	}
[f6660520]	185
[92976d9]	186	//=============================================================================================
	187	// I/O Submissions
	188	//=============================================================================================
	189
[2d8f7b0]	190	// Submition steps :
[e46c753]	191	// 1 - Allocate a queue entry. The ring already has memory for all entries but only the ones
[2d8f7b0]	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	//
[e46c753]	196	// 2 - Actually fill the submit entry, this is the only simple and straightforward step.
[2d8f7b0]	197	//
[e46c753]	198	// 3 - Append the entry index to the array and adjust the tail accordingly. This operation
[2d8f7b0]	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	//
[78da4ab]	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) {
[dddb3dd0]	211	__cfadbg_print_safe(io, "Kernel I/O : filling loop\n");
[78da4ab]	212	out_sqes[i] = &sqes[idxs[i]];
	213	}
	214	}
[2489d31]	215
[78da4ab]	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
[2489d31]	223
[78da4ab]	224	// If we don't have enough sqes, fail
	225	if((ftail - fhead) < want) { return false; }
[426f60c]	226
[78da4ab]	227	// copy all the indexes we want from the available list
	228	for(i; want) {
[dddb3dd0]	229	__cfadbg_print_safe(io, "Kernel I/O : allocating loop\n");
[78da4ab]	230	idxs[i] = sq.free_ring.array[(fhead + i) & mask];
[6f121b8]	231	}
[2489d31]	232
[78da4ab]	233	// Advance the head to mark the indexes as consumed
	234	__atomic_store_n(&sq.free_ring.head, fhead + want, __ATOMIC_RELEASE);
[df40a56]	235
[78da4ab]	236	// return success
	237	return true;
	238	}
[df40a56]	239
[78da4ab]	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);
[df40a56]	247
[78da4ab]	248	disable_interrupts();
	249	processor * proc = __cfaabi_tls.this_processor;
[dddb3dd0]	250	$io_context * ctx = proc->io.ctx;
[78da4ab]	251	/* paranoid */ verify( __cfaabi_tls.this_processor );
[dddb3dd0]	252	/* paranoid */ verify( ctx );
[78da4ab]	253
[dddb3dd0]	254	__cfadbg_print_safe(io, "Kernel I/O : attempting to fast allocation\n");
[78da4ab]	255
[dddb3dd0]	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; )
[a3821fa]	260	enable_interrupts();
[df40a56]	261
[dddb3dd0]	262	__cfadbg_print_safe(io, "Kernel I/O : fast allocation successful from ring %d\n", ctx->fd);
[2fafe7e]	263
[dddb3dd0]	264	__fill( sqes, want, idxs, ctx );
	265	return ctx;
[df40a56]	266	}
[dddb3dd0]	267	// The fast path failed, fallback
	268	__STATS__( true, io.alloc.fail += 1; )
[df40a56]	269
[78da4ab]	270	// Fast path failed, fallback on arbitration
[d60d30e]	271	__STATS__( true, io.alloc.slow += 1; )
[a3821fa]	272	enable_interrupts();
[78da4ab]	273
[dddb3dd0]	274	$io_arbiter * ioarb = proc->cltr->io.arbiter;
	275	/* paranoid */ verify( ioarb );
	276
[78da4ab]	277	__cfadbg_print_safe(io, "Kernel I/O : falling back on arbiter for allocation\n");
	278
[11054eb]	279	struct $io_context * ret = __ioarbiter_allocate(*ioarb, idxs, want);
[78da4ab]	280
[dddb3dd0]	281	__cfadbg_print_safe(io, "Kernel I/O : slow allocation completed from ring %d\n", ret->fd);
[df40a56]	282
[78da4ab]	283	__fill( sqes, want, idxs,ret );
	284	return ret;
[df40a56]	285	}
	286
[78da4ab]	287	//=============================================================================================
	288	// submission
[2432e8e]	289	static inline void __submit_only( struct $io_context * ctx, __u32 idxs[], __u32 have) {
[78da4ab]	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;
[dddb3dd0]	294	__u32 tail = *sq.kring.tail;
[78da4ab]	295
	296	// Add the sqes to the array
	297	for( i; have ) {
[dddb3dd0]	298	__cfadbg_print_safe(io, "Kernel I/O : __submit loop\n");
[78da4ab]	299	sq.kring.array[ (tail + i) & mask ] = idxs[i];
[426f60c]	300	}
	301
[78da4ab]	302	// Make the sqes visible to the submitter
[dddb3dd0]	303	__atomic_store_n(sq.kring.tail, tail + have, __ATOMIC_RELEASE);
[e8ac228]	304	sq.to_submit += have;
[426f60c]	305
[d529ad0]	306	__atomic_store_n(&ctx->proc->io.pending, true, __ATOMIC_RELAXED);
	307	__atomic_store_n(&ctx->proc->io.dirty , true, __ATOMIC_RELAXED);
[2432e8e]	308	}
	309
	310	static inline void __submit( struct $io_context * ctx, __u32 idxs[], __u32 have, bool lazy) {
	311	__sub_ring_t & sq = ctx->sq;
	312	__submit_only(ctx, idxs, have);
	313
[70b4aeb9]	314	if(sq.to_submit > 30) {
	315	__tls_stats()->io.flush.full++;
	316	__cfa_io_flush( ctx->proc, 0 );
	317	}
	318	if(!lazy) {
	319	__tls_stats()->io.flush.eager++;
[c7b2215]	320	__cfa_io_flush( ctx->proc, 0 );
[dddb3dd0]	321	}
[78da4ab]	322	}
[2489d31]	323
[dddb3dd0]	324	void cfa_io_submit( struct $io_context * inctx, __u32 idxs[], __u32 have, bool lazy ) __attribute__((nonnull (1))) {
	325	__cfadbg_print_safe(io, "Kernel I/O : attempting to submit %u (%s)\n", have, lazy ? "lazy" : "eager");
[5dadc9b7]	326
[78da4ab]	327	disable_interrupts();
	328	processor * proc = __cfaabi_tls.this_processor;
	329	$io_context * ctx = proc->io.ctx;
[dddb3dd0]	330	/* paranoid */ verify( __cfaabi_tls.this_processor );
	331	/* paranoid */ verify( ctx );
[e46c753]	332
[78da4ab]	333	// Can we proceed to the fast path
[dddb3dd0]	334	if( ctx == inctx ) // We have the right instance?
[78da4ab]	335	{
[dddb3dd0]	336	__submit(ctx, idxs, have, lazy);
[e46c753]	337
[78da4ab]	338	// Mark the instance as no longer in-use, re-enable interrupts and return
[d60d30e]	339	__STATS__( true, io.submit.fast += 1; )
[a3821fa]	340	enable_interrupts();
[ece0e80]	341
[78da4ab]	342	__cfadbg_print_safe(io, "Kernel I/O : submitted on fast path\n");
	343	return;
[e46c753]	344	}
[d384787]	345
[78da4ab]	346	// Fast path failed, fallback on arbitration
[d60d30e]	347	__STATS__( true, io.submit.slow += 1; )
[a3821fa]	348	enable_interrupts();
[5dadc9b7]	349
[78da4ab]	350	__cfadbg_print_safe(io, "Kernel I/O : falling back on arbiter for submission\n");
[426f60c]	351
[11054eb]	352	__ioarbiter_submit(inctx, idxs, have, lazy);
[78da4ab]	353	}
[2fab24e3]	354
[78da4ab]	355	//=============================================================================================
	356	// Flushing
[426f60c]	357	// Go through the ring's submit queue and release everything that has already been consumed
	358	// by io_uring
[78da4ab]	359	// This cannot be done by multiple threads
	360	static __u32 __release_sqes( struct $io_context & ctx ) {
	361	const __u32 mask = *ctx.sq.mask;
[732b406]	362
[426f60c]	363	__attribute__((unused))
[78da4ab]	364	__u32 ctail = *ctx.sq.kring.tail; // get the current tail of the queue
	365	__u32 chead = *ctx.sq.kring.head; // get the current head of the queue
	366	__u32 phead = ctx.sq.kring.released; // get the head the last time we were here
	367
	368	__u32 ftail = ctx.sq.free_ring.tail; // get the current tail of the queue
[732b406]	369
[426f60c]	370	// the 3 fields are organized like this diagram
	371	// except it's are ring
	372	// ---+--------+--------+----
	373	// ---+--------+--------+----
	374	// ^ ^ ^
	375	// phead chead ctail
	376
	377	// make sure ctail doesn't wrap around and reach phead
	378	/* paranoid */ verify(
	379	(ctail >= chead && chead >= phead)
	380	\|\| (chead >= phead && phead >= ctail)
	381	\|\| (phead >= ctail && ctail >= chead)
	382	);
	383
	384	// find the range we need to clear
[4998155]	385	__u32 count = chead - phead;
[426f60c]	386
[78da4ab]	387	if(count == 0) {
	388	return 0;
	389	}
	390
[426f60c]	391	// We acquired an previous-head/current-head range
	392	// go through the range and release the sqes
[34b61882]	393	for( i; count ) {
[dddb3dd0]	394	__cfadbg_print_safe(io, "Kernel I/O : release loop\n");
[78da4ab]	395	__u32 idx = ctx.sq.kring.array[ (phead + i) & mask ];
	396	ctx.sq.free_ring.array[ (ftail + i) & mask ] = idx;
[34b61882]	397	}
[78da4ab]	398
	399	ctx.sq.kring.released = chead; // note up to were we processed
	400	__atomic_store_n(&ctx.sq.free_ring.tail, ftail + count, __ATOMIC_SEQ_CST);
	401
	402	__ioarbiter_notify(ctx);
	403
[34b61882]	404	return count;
	405	}
[35285fd]	406
[78da4ab]	407	//=============================================================================================
	408	// I/O Arbiter
	409	//=============================================================================================
[9f5a71eb]	410	static inline bool enqueue(__outstanding_io_queue & queue, __outstanding_io & item) {
	411	bool was_empty;
	412
[11054eb]	413	// Lock the list, it's not thread safe
	414	lock( queue.lock __cfaabi_dbg_ctx2 );
	415	{
[9f5a71eb]	416	was_empty = empty(queue.queue);
	417
[11054eb]	418	// Add our request to the list
	419	add( queue.queue, item );
	420
	421	// Mark as pending
	422	__atomic_store_n( &queue.empty, false, __ATOMIC_SEQ_CST );
	423	}
	424	unlock( queue.lock );
	425
[9f5a71eb]	426	return was_empty;
[11054eb]	427	}
	428
	429	static inline bool empty(__outstanding_io_queue & queue ) {
	430	return __atomic_load_n( &queue.empty, __ATOMIC_SEQ_CST);
	431	}
	432
	433	static $io_context * __ioarbiter_allocate( $io_arbiter & this, __u32 idxs[], __u32 want ) {
[78da4ab]	434	__cfadbg_print_safe(io, "Kernel I/O : arbiter allocating\n");
	435
[d60d30e]	436	__STATS__( false, io.alloc.block += 1; )
	437
[78da4ab]	438	// No one has any resources left, wait for something to finish
[11054eb]	439	// We need to add ourself to a list of pending allocs and wait for an answer
	440	__pending_alloc pa;
	441	pa.idxs = idxs;
	442	pa.want = want;
[78da4ab]	443
[9f5a71eb]	444	enqueue(this.pending, (__outstanding_io&)pa);
	445
	446	wait( pa.sem );
[78da4ab]	447
[11054eb]	448	return pa.ctx;
[dddb3dd0]	449
[78da4ab]	450	}
	451
[11054eb]	452	static void __ioarbiter_notify( $io_arbiter & this, $io_context * ctx ) {
	453	/* paranoid */ verify( !empty(this.pending.queue) );
[78da4ab]	454
[11054eb]	455	lock( this.pending.lock __cfaabi_dbg_ctx2 );
	456	{
	457	while( !empty(this.pending.queue) ) {
	458	__cfadbg_print_safe(io, "Kernel I/O : notifying\n");
	459	__u32 have = ctx->sq.free_ring.tail - ctx->sq.free_ring.head;
	460	__pending_alloc & pa = (__pending_alloc&)head( this.pending.queue );
[78da4ab]	461
[11054eb]	462	if( have > pa.want ) goto DONE;
	463	drop( this.pending.queue );
[78da4ab]	464
[11054eb]	465	/* paranoid */__attribute__((unused)) bool ret =
[78da4ab]	466
[11054eb]	467	__alloc(ctx, pa.idxs, pa.want);
	468
	469	/* paranoid */ verify( ret );
	470
	471	pa.ctx = ctx;
	472
	473	post( pa.sem );
	474	}
	475
	476	this.pending.empty = true;
	477	DONE:;
	478	}
	479	unlock( this.pending.lock );
[78da4ab]	480	}
	481
	482	static void __ioarbiter_notify( $io_context & ctx ) {
[11054eb]	483	if(!empty( ctx.arbiter->pending )) {
[78da4ab]	484	__ioarbiter_notify( *ctx.arbiter, &ctx );
	485	}
	486	}
	487
	488	// Simply append to the pending
[11054eb]	489	static void __ioarbiter_submit( $io_context * ctx, __u32 idxs[], __u32 have, bool lazy ) {
[78da4ab]	490	__cfadbg_print_safe(io, "Kernel I/O : submitting %u from the arbiter to context %u\n", have, ctx->fd);
	491
	492	__cfadbg_print_safe(io, "Kernel I/O : waiting to submit %u\n", have);
	493
[11054eb]	494	__external_io ei;
	495	ei.idxs = idxs;
	496	ei.have = have;
	497	ei.lazy = lazy;
[78da4ab]	498
[9f5a71eb]	499	bool we = enqueue(ctx->ext_sq, (__outstanding_io&)ei);
	500
[d529ad0]	501	__atomic_store_n(&ctx->proc->io.pending, true, __ATOMIC_SEQ_CST);
[9f5a71eb]	502
	503	if( we ) {
	504	sigval_t value = { PREEMPT_IO };
	505	pthread_sigqueue(ctx->proc->kernel_thread, SIGUSR1, value);
	506	}
	507
	508	wait( ei.sem );
[78da4ab]	509
	510	__cfadbg_print_safe(io, "Kernel I/O : %u submitted from arbiter\n", have);
	511	}
	512
[11054eb]	513	static void __ioarbiter_flush( $io_context & ctx ) {
	514	if(!empty( ctx.ext_sq )) {
	515	__STATS__( false, io.flush.external += 1; )
[78da4ab]	516
[11054eb]	517	__cfadbg_print_safe(io, "Kernel I/O : arbiter flushing\n");
[d60d30e]	518
[11054eb]	519	lock( ctx.ext_sq.lock __cfaabi_dbg_ctx2 );
	520	{
	521	while( !empty(ctx.ext_sq.queue) ) {
	522	__external_io & ei = (__external_io&)drop( ctx.ext_sq.queue );
[78da4ab]	523
[2432e8e]	524	__submit_only(&ctx, ei.idxs, ei.have);
[78da4ab]	525
[11054eb]	526	post( ei.sem );
	527	}
	528
	529	ctx.ext_sq.empty = true;
	530	}
	531	unlock(ctx.ext_sq.lock );
	532	}
[78da4ab]	533	}
[7ef162b2]	534
[d3605f8]	535	#if defined(CFA_WITH_IO_URING_IDLE)
	536	bool __kernel_read(processor * proc, io_future_t & future, iovec & iov, int fd) {
[6ddef36]	537	$io_context * ctx = proc->io.ctx;
	538	/* paranoid */ verify( ! __preemption_enabled() );
	539	/* paranoid */ verify( proc == __cfaabi_tls.this_processor );
	540	/* paranoid */ verify( ctx );
[7ef162b2]	541
[6ddef36]	542	__u32 idx;
	543	struct io_uring_sqe * sqe;
[7ef162b2]	544
[6ddef36]	545	// We can proceed to the fast path
	546	if( !__alloc(ctx, &idx, 1) ) return false;
	547
	548	// Allocation was successful
	549	__fill( &sqe, 1, &idx, ctx );
	550
	551	sqe->user_data = (uintptr_t)&future;
	552	sqe->flags = 0;
[a1f3d93]	553	sqe->fd = fd;
[6ddef36]	554	sqe->off = 0;
[d3605f8]	555	sqe->ioprio = 0;
[6ddef36]	556	sqe->fsync_flags = 0;
	557	sqe->__pad2[0] = 0;
	558	sqe->__pad2[1] = 0;
	559	sqe->__pad2[2] = 0;
[d3605f8]	560
	561	#if defined(CFA_HAVE_IORING_OP_READ)
	562	sqe->opcode = IORING_OP_READ;
	563	sqe->addr = (uint64_t)iov.iov_base;
	564	sqe->len = iov.iov_len;
	565	#elif defined(CFA_HAVE_READV) && defined(CFA_HAVE_IORING_OP_READV)
	566	sqe->opcode = IORING_OP_READV;
	567	sqe->addr = (uintptr_t)&iov;
	568	sqe->len = 1;
	569	#else
	570	#error CFA_WITH_IO_URING_IDLE but none of CFA_HAVE_READV, CFA_HAVE_IORING_OP_READV or CFA_HAVE_IORING_OP_READ defined
	571	#endif
[6ddef36]	572
	573	asm volatile("": : :"memory");
	574
	575	/* paranoid */ verify( sqe->user_data == (uintptr_t)&future );
	576	__submit( ctx, &idx, 1, true );
	577
	578	/* paranoid */ verify( proc == __cfaabi_tls.this_processor );
	579	/* paranoid */ verify( ! __preemption_enabled() );
[078fb05]	580
	581	return true;
[6ddef36]	582	}
	583	#endif
[47746a2]	584	#endif

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