1 /* 2 * QEMU aio implementation 3 * 4 * Copyright IBM, Corp. 2008 5 * 6 * Authors: 7 * Anthony Liguori <aliguori@us.ibm.com> 8 * 9 * This work is licensed under the terms of the GNU GPL, version 2. See 10 * the COPYING file in the top-level directory. 11 * 12 */ 13 14 #ifndef QEMU_AIO_H 15 #define QEMU_AIO_H 16 17 #ifdef CONFIG_LINUX_IO_URING 18 #include <liburing.h> 19 #endif 20 #include "qemu/coroutine-core.h" 21 #include "qemu/queue.h" 22 #include "qemu/event_notifier.h" 23 #include "qemu/thread.h" 24 #include "qemu/timer.h" 25 #include "block/graph-lock.h" 26 27 typedef struct BlockAIOCB BlockAIOCB; 28 typedef void BlockCompletionFunc(void *opaque, int ret); 29 30 typedef struct AIOCBInfo { 31 void (*cancel_async)(BlockAIOCB *acb); 32 AioContext *(*get_aio_context)(BlockAIOCB *acb); 33 size_t aiocb_size; 34 } AIOCBInfo; 35 36 struct BlockAIOCB { 37 const AIOCBInfo *aiocb_info; 38 BlockDriverState *bs; 39 BlockCompletionFunc *cb; 40 void *opaque; 41 int refcnt; 42 }; 43 44 void *qemu_aio_get(const AIOCBInfo *aiocb_info, BlockDriverState *bs, 45 BlockCompletionFunc *cb, void *opaque); 46 void qemu_aio_unref(void *p); 47 void qemu_aio_ref(void *p); 48 49 typedef struct AioHandler AioHandler; 50 typedef QLIST_HEAD(, AioHandler) AioHandlerList; 51 typedef void QEMUBHFunc(void *opaque); 52 typedef bool AioPollFn(void *opaque); 53 typedef void IOHandler(void *opaque); 54 55 struct ThreadPool; 56 struct LinuxAioState; 57 struct LuringState; 58 59 /* Is polling disabled? */ 60 bool aio_poll_disabled(AioContext *ctx); 61 62 /* Callbacks for file descriptor monitoring implementations */ 63 typedef struct { 64 /* 65 * update: 66 * @ctx: the AioContext 67 * @old_node: the existing handler or NULL if this file descriptor is being 68 * monitored for the first time 69 * @new_node: the new handler or NULL if this file descriptor is being 70 * removed 71 * 72 * Add/remove/modify a monitored file descriptor. 73 * 74 * Called with ctx->list_lock acquired. 75 */ 76 void (*update)(AioContext *ctx, AioHandler *old_node, AioHandler *new_node); 77 78 /* 79 * wait: 80 * @ctx: the AioContext 81 * @ready_list: list for handlers that become ready 82 * @timeout: maximum duration to wait, in nanoseconds 83 * 84 * Wait for file descriptors to become ready and place them on ready_list. 85 * 86 * Called with ctx->list_lock incremented but not locked. 87 * 88 * Returns: number of ready file descriptors. 89 */ 90 int (*wait)(AioContext *ctx, AioHandlerList *ready_list, int64_t timeout); 91 92 /* 93 * need_wait: 94 * @ctx: the AioContext 95 * 96 * Tell aio_poll() when to stop userspace polling early because ->wait() 97 * has fds ready. 98 * 99 * File descriptor monitoring implementations that cannot poll fd readiness 100 * from userspace should use aio_poll_disabled() here. This ensures that 101 * file descriptors are not starved by handlers that frequently make 102 * progress via userspace polling. 103 * 104 * Returns: true if ->wait() should be called, false otherwise. 105 */ 106 bool (*need_wait)(AioContext *ctx); 107 } FDMonOps; 108 109 /* 110 * Each aio_bh_poll() call carves off a slice of the BH list, so that newly 111 * scheduled BHs are not processed until the next aio_bh_poll() call. All 112 * active aio_bh_poll() calls chain their slices together in a list, so that 113 * nested aio_bh_poll() calls process all scheduled bottom halves. 114 */ 115 typedef QSLIST_HEAD(, QEMUBH) BHList; 116 typedef struct BHListSlice BHListSlice; 117 struct BHListSlice { 118 BHList bh_list; 119 QSIMPLEQ_ENTRY(BHListSlice) next; 120 }; 121 122 typedef QSLIST_HEAD(, AioHandler) AioHandlerSList; 123 124 struct AioContext { 125 GSource source; 126 127 /* Used by AioContext users to protect from multi-threaded access. */ 128 QemuRecMutex lock; 129 130 /* 131 * Keep track of readers and writers of the block layer graph. 132 * This is essential to avoid performing additions and removal 133 * of nodes and edges from block graph while some 134 * other thread is traversing it. 135 */ 136 BdrvGraphRWlock *bdrv_graph; 137 138 /* The list of registered AIO handlers. Protected by ctx->list_lock. */ 139 AioHandlerList aio_handlers; 140 141 /* The list of AIO handlers to be deleted. Protected by ctx->list_lock. */ 142 AioHandlerList deleted_aio_handlers; 143 144 /* Used to avoid unnecessary event_notifier_set calls in aio_notify; 145 * only written from the AioContext home thread, or under the BQL in 146 * the case of the main AioContext. However, it is read from any 147 * thread so it is still accessed with atomic primitives. 148 * 149 * If this field is 0, everything (file descriptors, bottom halves, 150 * timers) will be re-evaluated before the next blocking poll() or 151 * io_uring wait; therefore, the event_notifier_set call can be 152 * skipped. If it is non-zero, you may need to wake up a concurrent 153 * aio_poll or the glib main event loop, making event_notifier_set 154 * necessary. 155 * 156 * Bit 0 is reserved for GSource usage of the AioContext, and is 1 157 * between a call to aio_ctx_prepare and the next call to aio_ctx_check. 158 * Bits 1-31 simply count the number of active calls to aio_poll 159 * that are in the prepare or poll phase. 160 * 161 * The GSource and aio_poll must use a different mechanism because 162 * there is no certainty that a call to GSource's prepare callback 163 * (via g_main_context_prepare) is indeed followed by check and 164 * dispatch. It's not clear whether this would be a bug, but let's 165 * play safe and allow it---it will just cause extra calls to 166 * event_notifier_set until the next call to dispatch. 167 * 168 * Instead, the aio_poll calls include both the prepare and the 169 * dispatch phase, hence a simple counter is enough for them. 170 */ 171 uint32_t notify_me; 172 173 /* A lock to protect between QEMUBH and AioHandler adders and deleter, 174 * and to ensure that no callbacks are removed while we're walking and 175 * dispatching them. 176 */ 177 QemuLockCnt list_lock; 178 179 /* Bottom Halves pending aio_bh_poll() processing */ 180 BHList bh_list; 181 182 /* Chained BH list slices for each nested aio_bh_poll() call */ 183 QSIMPLEQ_HEAD(, BHListSlice) bh_slice_list; 184 185 /* Used by aio_notify. 186 * 187 * "notified" is used to avoid expensive event_notifier_test_and_clear 188 * calls. When it is clear, the EventNotifier is clear, or one thread 189 * is going to clear "notified" before processing more events. False 190 * positives are possible, i.e. "notified" could be set even though the 191 * EventNotifier is clear. 192 * 193 * Note that event_notifier_set *cannot* be optimized the same way. For 194 * more information on the problem that would result, see "#ifdef BUG2" 195 * in the docs/aio_notify_accept.promela formal model. 196 */ 197 bool notified; 198 EventNotifier notifier; 199 200 QSLIST_HEAD(, Coroutine) scheduled_coroutines; 201 QEMUBH *co_schedule_bh; 202 203 int thread_pool_min; 204 int thread_pool_max; 205 /* Thread pool for performing work and receiving completion callbacks. 206 * Has its own locking. 207 */ 208 struct ThreadPool *thread_pool; 209 210 #ifdef CONFIG_LINUX_AIO 211 /* 212 * State for native Linux AIO. Uses aio_context_acquire/release for 213 * locking. 214 */ 215 struct LinuxAioState *linux_aio; 216 #endif 217 #ifdef CONFIG_LINUX_IO_URING 218 /* 219 * State for Linux io_uring. Uses aio_context_acquire/release for 220 * locking. 221 */ 222 struct LuringState *linux_io_uring; 223 224 /* State for file descriptor monitoring using Linux io_uring */ 225 struct io_uring fdmon_io_uring; 226 AioHandlerSList submit_list; 227 #endif 228 229 /* TimerLists for calling timers - one per clock type. Has its own 230 * locking. 231 */ 232 QEMUTimerListGroup tlg; 233 234 int external_disable_cnt; 235 236 /* Number of AioHandlers without .io_poll() */ 237 int poll_disable_cnt; 238 239 /* Polling mode parameters */ 240 int64_t poll_ns; /* current polling time in nanoseconds */ 241 int64_t poll_max_ns; /* maximum polling time in nanoseconds */ 242 int64_t poll_grow; /* polling time growth factor */ 243 int64_t poll_shrink; /* polling time shrink factor */ 244 245 /* AIO engine parameters */ 246 int64_t aio_max_batch; /* maximum number of requests in a batch */ 247 248 /* 249 * List of handlers participating in userspace polling. Protected by 250 * ctx->list_lock. Iterated and modified mostly by the event loop thread 251 * from aio_poll() with ctx->list_lock incremented. aio_set_fd_handler() 252 * only touches the list to delete nodes if ctx->list_lock's count is zero. 253 */ 254 AioHandlerList poll_aio_handlers; 255 256 /* Are we in polling mode or monitoring file descriptors? */ 257 bool poll_started; 258 259 /* epoll(7) state used when built with CONFIG_EPOLL */ 260 int epollfd; 261 262 const FDMonOps *fdmon_ops; 263 }; 264 265 /** 266 * aio_context_new: Allocate a new AioContext. 267 * 268 * AioContext provide a mini event-loop that can be waited on synchronously. 269 * They also provide bottom halves, a service to execute a piece of code 270 * as soon as possible. 271 */ 272 AioContext *aio_context_new(Error **errp); 273 274 /** 275 * aio_context_ref: 276 * @ctx: The AioContext to operate on. 277 * 278 * Add a reference to an AioContext. 279 */ 280 void aio_context_ref(AioContext *ctx); 281 282 /** 283 * aio_context_unref: 284 * @ctx: The AioContext to operate on. 285 * 286 * Drop a reference to an AioContext. 287 */ 288 void aio_context_unref(AioContext *ctx); 289 290 /* Take ownership of the AioContext. If the AioContext will be shared between 291 * threads, and a thread does not want to be interrupted, it will have to 292 * take ownership around calls to aio_poll(). Otherwise, aio_poll() 293 * automatically takes care of calling aio_context_acquire and 294 * aio_context_release. 295 * 296 * Note that this is separate from bdrv_drained_begin/bdrv_drained_end. A 297 * thread still has to call those to avoid being interrupted by the guest. 298 * 299 * Bottom halves, timers and callbacks can be created or removed without 300 * acquiring the AioContext. 301 */ 302 void aio_context_acquire(AioContext *ctx); 303 304 /* Relinquish ownership of the AioContext. */ 305 void aio_context_release(AioContext *ctx); 306 307 /** 308 * aio_bh_schedule_oneshot_full: Allocate a new bottom half structure that will 309 * run only once and as soon as possible. 310 * 311 * @name: A human-readable identifier for debugging purposes. 312 */ 313 void aio_bh_schedule_oneshot_full(AioContext *ctx, QEMUBHFunc *cb, void *opaque, 314 const char *name); 315 316 /** 317 * aio_bh_schedule_oneshot: Allocate a new bottom half structure that will run 318 * only once and as soon as possible. 319 * 320 * A convenience wrapper for aio_bh_schedule_oneshot_full() that uses cb as the 321 * name string. 322 */ 323 #define aio_bh_schedule_oneshot(ctx, cb, opaque) \ 324 aio_bh_schedule_oneshot_full((ctx), (cb), (opaque), (stringify(cb))) 325 326 /** 327 * aio_bh_new_full: Allocate a new bottom half structure. 328 * 329 * Bottom halves are lightweight callbacks whose invocation is guaranteed 330 * to be wait-free, thread-safe and signal-safe. The #QEMUBH structure 331 * is opaque and must be allocated prior to its use. 332 * 333 * @name: A human-readable identifier for debugging purposes. 334 */ 335 QEMUBH *aio_bh_new_full(AioContext *ctx, QEMUBHFunc *cb, void *opaque, 336 const char *name); 337 338 /** 339 * aio_bh_new: Allocate a new bottom half structure 340 * 341 * A convenience wrapper for aio_bh_new_full() that uses the cb as the name 342 * string. 343 */ 344 #define aio_bh_new(ctx, cb, opaque) \ 345 aio_bh_new_full((ctx), (cb), (opaque), (stringify(cb))) 346 347 /** 348 * aio_notify: Force processing of pending events. 349 * 350 * Similar to signaling a condition variable, aio_notify forces 351 * aio_poll to exit, so that the next call will re-examine pending events. 352 * The caller of aio_notify will usually call aio_poll again very soon, 353 * or go through another iteration of the GLib main loop. Hence, aio_notify 354 * also has the side effect of recalculating the sets of file descriptors 355 * that the main loop waits for. 356 * 357 * Calling aio_notify is rarely necessary, because for example scheduling 358 * a bottom half calls it already. 359 */ 360 void aio_notify(AioContext *ctx); 361 362 /** 363 * aio_notify_accept: Acknowledge receiving an aio_notify. 364 * 365 * aio_notify() uses an EventNotifier in order to wake up a sleeping 366 * aio_poll() or g_main_context_iteration(). Calls to aio_notify() are 367 * usually rare, but the AioContext has to clear the EventNotifier on 368 * every aio_poll() or g_main_context_iteration() in order to avoid 369 * busy waiting. This event_notifier_test_and_clear() cannot be done 370 * using the usual aio_context_set_event_notifier(), because it must 371 * be done before processing all events (file descriptors, bottom halves, 372 * timers). 373 * 374 * aio_notify_accept() is an optimized event_notifier_test_and_clear() 375 * that is specific to an AioContext's notifier; it is used internally 376 * to clear the EventNotifier only if aio_notify() had been called. 377 */ 378 void aio_notify_accept(AioContext *ctx); 379 380 /** 381 * aio_bh_call: Executes callback function of the specified BH. 382 */ 383 void aio_bh_call(QEMUBH *bh); 384 385 /** 386 * aio_bh_poll: Poll bottom halves for an AioContext. 387 * 388 * These are internal functions used by the QEMU main loop. 389 * And notice that multiple occurrences of aio_bh_poll cannot 390 * be called concurrently 391 */ 392 int aio_bh_poll(AioContext *ctx); 393 394 /** 395 * qemu_bh_schedule: Schedule a bottom half. 396 * 397 * Scheduling a bottom half interrupts the main loop and causes the 398 * execution of the callback that was passed to qemu_bh_new. 399 * 400 * Bottom halves that are scheduled from a bottom half handler are instantly 401 * invoked. This can create an infinite loop if a bottom half handler 402 * schedules itself. 403 * 404 * @bh: The bottom half to be scheduled. 405 */ 406 void qemu_bh_schedule(QEMUBH *bh); 407 408 /** 409 * qemu_bh_cancel: Cancel execution of a bottom half. 410 * 411 * Canceling execution of a bottom half undoes the effect of calls to 412 * qemu_bh_schedule without freeing its resources yet. While cancellation 413 * itself is also wait-free and thread-safe, it can of course race with the 414 * loop that executes bottom halves unless you are holding the iothread 415 * mutex. This makes it mostly useless if you are not holding the mutex. 416 * 417 * @bh: The bottom half to be canceled. 418 */ 419 void qemu_bh_cancel(QEMUBH *bh); 420 421 /** 422 *qemu_bh_delete: Cancel execution of a bottom half and free its resources. 423 * 424 * Deleting a bottom half frees the memory that was allocated for it by 425 * qemu_bh_new. It also implies canceling the bottom half if it was 426 * scheduled. 427 * This func is async. The bottom half will do the delete action at the finial 428 * end. 429 * 430 * @bh: The bottom half to be deleted. 431 */ 432 void qemu_bh_delete(QEMUBH *bh); 433 434 /* Return whether there are any pending callbacks from the GSource 435 * attached to the AioContext, before g_poll is invoked. 436 * 437 * This is used internally in the implementation of the GSource. 438 */ 439 bool aio_prepare(AioContext *ctx); 440 441 /* Return whether there are any pending callbacks from the GSource 442 * attached to the AioContext, after g_poll is invoked. 443 * 444 * This is used internally in the implementation of the GSource. 445 */ 446 bool aio_pending(AioContext *ctx); 447 448 /* Dispatch any pending callbacks from the GSource attached to the AioContext. 449 * 450 * This is used internally in the implementation of the GSource. 451 */ 452 void aio_dispatch(AioContext *ctx); 453 454 /* Progress in completing AIO work to occur. This can issue new pending 455 * aio as a result of executing I/O completion or bh callbacks. 456 * 457 * Return whether any progress was made by executing AIO or bottom half 458 * handlers. If @blocking == true, this should always be true except 459 * if someone called aio_notify. 460 * 461 * If there are no pending bottom halves, but there are pending AIO 462 * operations, it may not be possible to make any progress without 463 * blocking. If @blocking is true, this function will wait until one 464 * or more AIO events have completed, to ensure something has moved 465 * before returning. 466 */ 467 bool aio_poll(AioContext *ctx, bool blocking); 468 469 /* Register a file descriptor and associated callbacks. Behaves very similarly 470 * to qemu_set_fd_handler. Unlike qemu_set_fd_handler, these callbacks will 471 * be invoked when using aio_poll(). 472 * 473 * Code that invokes AIO completion functions should rely on this function 474 * instead of qemu_set_fd_handler[2]. 475 */ 476 void aio_set_fd_handler(AioContext *ctx, 477 int fd, 478 bool is_external, 479 IOHandler *io_read, 480 IOHandler *io_write, 481 AioPollFn *io_poll, 482 IOHandler *io_poll_ready, 483 void *opaque); 484 485 /* Register an event notifier and associated callbacks. Behaves very similarly 486 * to event_notifier_set_handler. Unlike event_notifier_set_handler, these callbacks 487 * will be invoked when using aio_poll(). 488 * 489 * Code that invokes AIO completion functions should rely on this function 490 * instead of event_notifier_set_handler. 491 */ 492 void aio_set_event_notifier(AioContext *ctx, 493 EventNotifier *notifier, 494 bool is_external, 495 EventNotifierHandler *io_read, 496 AioPollFn *io_poll, 497 EventNotifierHandler *io_poll_ready); 498 499 /* Set polling begin/end callbacks for an event notifier that has already been 500 * registered with aio_set_event_notifier. Do nothing if the event notifier is 501 * not registered. 502 */ 503 void aio_set_event_notifier_poll(AioContext *ctx, 504 EventNotifier *notifier, 505 EventNotifierHandler *io_poll_begin, 506 EventNotifierHandler *io_poll_end); 507 508 /* Return a GSource that lets the main loop poll the file descriptors attached 509 * to this AioContext. 510 */ 511 GSource *aio_get_g_source(AioContext *ctx); 512 513 /* Return the ThreadPool bound to this AioContext */ 514 struct ThreadPool *aio_get_thread_pool(AioContext *ctx); 515 516 /* Setup the LinuxAioState bound to this AioContext */ 517 struct LinuxAioState *aio_setup_linux_aio(AioContext *ctx, Error **errp); 518 519 /* Return the LinuxAioState bound to this AioContext */ 520 struct LinuxAioState *aio_get_linux_aio(AioContext *ctx); 521 522 /* Setup the LuringState bound to this AioContext */ 523 struct LuringState *aio_setup_linux_io_uring(AioContext *ctx, Error **errp); 524 525 /* Return the LuringState bound to this AioContext */ 526 struct LuringState *aio_get_linux_io_uring(AioContext *ctx); 527 /** 528 * aio_timer_new_with_attrs: 529 * @ctx: the aio context 530 * @type: the clock type 531 * @scale: the scale 532 * @attributes: 0, or one to multiple OR'ed QEMU_TIMER_ATTR_<id> values 533 * to assign 534 * @cb: the callback to call on timer expiry 535 * @opaque: the opaque pointer to pass to the callback 536 * 537 * Allocate a new timer (with attributes) attached to the context @ctx. 538 * The function is responsible for memory allocation. 539 * 540 * The preferred interface is aio_timer_init or aio_timer_init_with_attrs. 541 * Use that unless you really need dynamic memory allocation. 542 * 543 * Returns: a pointer to the new timer 544 */ 545 static inline QEMUTimer *aio_timer_new_with_attrs(AioContext *ctx, 546 QEMUClockType type, 547 int scale, int attributes, 548 QEMUTimerCB *cb, void *opaque) 549 { 550 return timer_new_full(&ctx->tlg, type, scale, attributes, cb, opaque); 551 } 552 553 /** 554 * aio_timer_new: 555 * @ctx: the aio context 556 * @type: the clock type 557 * @scale: the scale 558 * @cb: the callback to call on timer expiry 559 * @opaque: the opaque pointer to pass to the callback 560 * 561 * Allocate a new timer attached to the context @ctx. 562 * See aio_timer_new_with_attrs for details. 563 * 564 * Returns: a pointer to the new timer 565 */ 566 static inline QEMUTimer *aio_timer_new(AioContext *ctx, QEMUClockType type, 567 int scale, 568 QEMUTimerCB *cb, void *opaque) 569 { 570 return timer_new_full(&ctx->tlg, type, scale, 0, cb, opaque); 571 } 572 573 /** 574 * aio_timer_init_with_attrs: 575 * @ctx: the aio context 576 * @ts: the timer 577 * @type: the clock type 578 * @scale: the scale 579 * @attributes: 0, or one to multiple OR'ed QEMU_TIMER_ATTR_<id> values 580 * to assign 581 * @cb: the callback to call on timer expiry 582 * @opaque: the opaque pointer to pass to the callback 583 * 584 * Initialise a new timer (with attributes) attached to the context @ctx. 585 * The caller is responsible for memory allocation. 586 */ 587 static inline void aio_timer_init_with_attrs(AioContext *ctx, 588 QEMUTimer *ts, QEMUClockType type, 589 int scale, int attributes, 590 QEMUTimerCB *cb, void *opaque) 591 { 592 timer_init_full(ts, &ctx->tlg, type, scale, attributes, cb, opaque); 593 } 594 595 /** 596 * aio_timer_init: 597 * @ctx: the aio context 598 * @ts: the timer 599 * @type: the clock type 600 * @scale: the scale 601 * @cb: the callback to call on timer expiry 602 * @opaque: the opaque pointer to pass to the callback 603 * 604 * Initialise a new timer attached to the context @ctx. 605 * See aio_timer_init_with_attrs for details. 606 */ 607 static inline void aio_timer_init(AioContext *ctx, 608 QEMUTimer *ts, QEMUClockType type, 609 int scale, 610 QEMUTimerCB *cb, void *opaque) 611 { 612 timer_init_full(ts, &ctx->tlg, type, scale, 0, cb, opaque); 613 } 614 615 /** 616 * aio_compute_timeout: 617 * @ctx: the aio context 618 * 619 * Compute the timeout that a blocking aio_poll should use. 620 */ 621 int64_t aio_compute_timeout(AioContext *ctx); 622 623 /** 624 * aio_disable_external: 625 * @ctx: the aio context 626 * 627 * Disable the further processing of external clients. 628 */ 629 static inline void aio_disable_external(AioContext *ctx) 630 { 631 qatomic_inc(&ctx->external_disable_cnt); 632 } 633 634 /** 635 * aio_enable_external: 636 * @ctx: the aio context 637 * 638 * Enable the processing of external clients. 639 */ 640 static inline void aio_enable_external(AioContext *ctx) 641 { 642 int old; 643 644 old = qatomic_fetch_dec(&ctx->external_disable_cnt); 645 assert(old > 0); 646 if (old == 1) { 647 /* Kick event loop so it re-arms file descriptors */ 648 aio_notify(ctx); 649 } 650 } 651 652 /** 653 * aio_external_disabled: 654 * @ctx: the aio context 655 * 656 * Return true if the external clients are disabled. 657 */ 658 static inline bool aio_external_disabled(AioContext *ctx) 659 { 660 return qatomic_read(&ctx->external_disable_cnt); 661 } 662 663 /** 664 * aio_node_check: 665 * @ctx: the aio context 666 * @is_external: Whether or not the checked node is an external event source. 667 * 668 * Check if the node's is_external flag is okay to be polled by the ctx at this 669 * moment. True means green light. 670 */ 671 static inline bool aio_node_check(AioContext *ctx, bool is_external) 672 { 673 return !is_external || !qatomic_read(&ctx->external_disable_cnt); 674 } 675 676 /** 677 * aio_co_schedule: 678 * @ctx: the aio context 679 * @co: the coroutine 680 * 681 * Start a coroutine on a remote AioContext. 682 * 683 * The coroutine must not be entered by anyone else while aio_co_schedule() 684 * is active. In addition the coroutine must have yielded unless ctx 685 * is the context in which the coroutine is running (i.e. the value of 686 * qemu_get_current_aio_context() from the coroutine itself). 687 */ 688 void aio_co_schedule(AioContext *ctx, Coroutine *co); 689 690 /** 691 * aio_co_reschedule_self: 692 * @new_ctx: the new context 693 * 694 * Move the currently running coroutine to new_ctx. If the coroutine is already 695 * running in new_ctx, do nothing. 696 */ 697 void coroutine_fn aio_co_reschedule_self(AioContext *new_ctx); 698 699 /** 700 * aio_co_wake: 701 * @co: the coroutine 702 * 703 * Restart a coroutine on the AioContext where it was running last, thus 704 * preventing coroutines from jumping from one context to another when they 705 * go to sleep. 706 * 707 * aio_co_wake may be executed either in coroutine or non-coroutine 708 * context. The coroutine must not be entered by anyone else while 709 * aio_co_wake() is active. 710 */ 711 void aio_co_wake(Coroutine *co); 712 713 /** 714 * aio_co_enter: 715 * @ctx: the context to run the coroutine 716 * @co: the coroutine to run 717 * 718 * Enter a coroutine in the specified AioContext. 719 */ 720 void aio_co_enter(AioContext *ctx, Coroutine *co); 721 722 /** 723 * Return the AioContext whose event loop runs in the current thread. 724 * 725 * If called from an IOThread this will be the IOThread's AioContext. If 726 * called from the main thread or with the "big QEMU lock" taken it 727 * will be the main loop AioContext. 728 */ 729 AioContext *qemu_get_current_aio_context(void); 730 731 void qemu_set_current_aio_context(AioContext *ctx); 732 733 /** 734 * aio_context_setup: 735 * @ctx: the aio context 736 * 737 * Initialize the aio context. 738 */ 739 void aio_context_setup(AioContext *ctx); 740 741 /** 742 * aio_context_destroy: 743 * @ctx: the aio context 744 * 745 * Destroy the aio context. 746 */ 747 void aio_context_destroy(AioContext *ctx); 748 749 /* Used internally, do not call outside AioContext code */ 750 void aio_context_use_g_source(AioContext *ctx); 751 752 /** 753 * aio_context_set_poll_params: 754 * @ctx: the aio context 755 * @max_ns: how long to busy poll for, in nanoseconds 756 * @grow: polling time growth factor 757 * @shrink: polling time shrink factor 758 * 759 * Poll mode can be disabled by setting poll_max_ns to 0. 760 */ 761 void aio_context_set_poll_params(AioContext *ctx, int64_t max_ns, 762 int64_t grow, int64_t shrink, 763 Error **errp); 764 765 /** 766 * aio_context_set_aio_params: 767 * @ctx: the aio context 768 * @max_batch: maximum number of requests in a batch, 0 means that the 769 * engine will use its default 770 */ 771 void aio_context_set_aio_params(AioContext *ctx, int64_t max_batch, 772 Error **errp); 773 774 /** 775 * aio_context_set_thread_pool_params: 776 * @ctx: the aio context 777 * @min: min number of threads to have readily available in the thread pool 778 * @min: max number of threads the thread pool can contain 779 */ 780 void aio_context_set_thread_pool_params(AioContext *ctx, int64_t min, 781 int64_t max, Error **errp); 782 #endif 783