diff options
| -rw-r--r-- | util/aio-posix.c | 59 | ||||
| -rw-r--r-- | util/trace-events | 4 |
2 files changed, 36 insertions, 27 deletions
diff --git a/util/aio-posix.c b/util/aio-posix.c index 5c29380..c54d1eb 100644 --- a/util/aio-posix.c +++ b/util/aio-posix.c @@ -490,7 +490,7 @@ static void add_pollfd(AioHandler *node) npfd++; } -static bool run_poll_handlers_once(AioContext *ctx) +static bool run_poll_handlers_once(AioContext *ctx, int64_t *timeout) { bool progress = false; AioHandler *node; @@ -500,6 +500,7 @@ static bool run_poll_handlers_once(AioContext *ctx) aio_node_check(ctx, node->is_external) && node->io_poll(node->opaque) && node->opaque != &ctx->notifier) { + *timeout = 0; progress = true; } @@ -522,31 +523,38 @@ static bool run_poll_handlers_once(AioContext *ctx) * * Returns: true if progress was made, false otherwise */ -static bool run_poll_handlers(AioContext *ctx, int64_t max_ns) +static bool run_poll_handlers(AioContext *ctx, int64_t max_ns, int64_t *timeout) { bool progress; - int64_t end_time; + int64_t start_time, elapsed_time; assert(ctx->notify_me); assert(qemu_lockcnt_count(&ctx->list_lock) > 0); - trace_run_poll_handlers_begin(ctx, max_ns); - - end_time = qemu_clock_get_ns(QEMU_CLOCK_REALTIME) + max_ns; + trace_run_poll_handlers_begin(ctx, max_ns, *timeout); + start_time = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); do { - progress = run_poll_handlers_once(ctx); - } while (!progress && qemu_clock_get_ns(QEMU_CLOCK_REALTIME) < end_time + progress = run_poll_handlers_once(ctx, timeout); + elapsed_time = qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - start_time; + } while (!progress && elapsed_time < max_ns && !atomic_read(&ctx->poll_disable_cnt)); - trace_run_poll_handlers_end(ctx, progress); + /* If time has passed with no successful polling, adjust *timeout to + * keep the same ending time. + */ + if (*timeout != -1) { + *timeout -= MIN(*timeout, elapsed_time); + } + trace_run_poll_handlers_end(ctx, progress, *timeout); return progress; } /* try_poll_mode: * @ctx: the AioContext - * @blocking: busy polling is only attempted when blocking is true + * @timeout: timeout for blocking wait, computed by the caller and updated if + * polling succeeds. * * ctx->notify_me must be non-zero so this function can detect aio_notify(). * @@ -554,19 +562,16 @@ static bool run_poll_handlers(AioContext *ctx, int64_t max_ns) * * Returns: true if progress was made, false otherwise */ -static bool try_poll_mode(AioContext *ctx, bool blocking) +static bool try_poll_mode(AioContext *ctx, int64_t *timeout) { - if (blocking && ctx->poll_max_ns && !atomic_read(&ctx->poll_disable_cnt)) { - /* See qemu_soonest_timeout() uint64_t hack */ - int64_t max_ns = MIN((uint64_t)aio_compute_timeout(ctx), - (uint64_t)ctx->poll_ns); + /* See qemu_soonest_timeout() uint64_t hack */ + int64_t max_ns = MIN((uint64_t)*timeout, (uint64_t)ctx->poll_ns); - if (max_ns) { - poll_set_started(ctx, true); + if (max_ns && !atomic_read(&ctx->poll_disable_cnt)) { + poll_set_started(ctx, true); - if (run_poll_handlers(ctx, max_ns)) { - return true; - } + if (run_poll_handlers(ctx, max_ns, timeout)) { + return true; } } @@ -575,7 +580,7 @@ static bool try_poll_mode(AioContext *ctx, bool blocking) /* Even if we don't run busy polling, try polling once in case it can make * progress and the caller will be able to avoid ppoll(2)/epoll_wait(2). */ - return run_poll_handlers_once(ctx); + return run_poll_handlers_once(ctx, timeout); } bool aio_poll(AioContext *ctx, bool blocking) @@ -605,8 +610,14 @@ bool aio_poll(AioContext *ctx, bool blocking) start = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); } - progress = try_poll_mode(ctx, blocking); - if (!progress) { + timeout = blocking ? aio_compute_timeout(ctx) : 0; + progress = try_poll_mode(ctx, &timeout); + assert(!(timeout && progress)); + + /* If polling is allowed, non-blocking aio_poll does not need the + * system call---a single round of run_poll_handlers_once suffices. + */ + if (timeout || atomic_read(&ctx->poll_disable_cnt)) { assert(npfd == 0); /* fill pollfds */ @@ -620,8 +631,6 @@ bool aio_poll(AioContext *ctx, bool blocking) } } - timeout = blocking ? aio_compute_timeout(ctx) : 0; - /* wait until next event */ if (aio_epoll_check_poll(ctx, pollfds, npfd, timeout)) { AioHandler epoll_handler; diff --git a/util/trace-events b/util/trace-events index 4822434..79569b7 100644 --- a/util/trace-events +++ b/util/trace-events @@ -1,8 +1,8 @@ # See docs/devel/tracing.txt for syntax documentation. # util/aio-posix.c -run_poll_handlers_begin(void *ctx, int64_t max_ns) "ctx %p max_ns %"PRId64 -run_poll_handlers_end(void *ctx, bool progress) "ctx %p progress %d" +run_poll_handlers_begin(void *ctx, int64_t max_ns, int64_t timeout) "ctx %p max_ns %"PRId64 " timeout %"PRId64 +run_poll_handlers_end(void *ctx, bool progress, int64_t timeout) "ctx %p progress %d new timeout %"PRId64 poll_shrink(void *ctx, int64_t old, int64_t new) "ctx %p old %"PRId64" new %"PRId64 poll_grow(void *ctx, int64_t old, int64_t new) "ctx %p old %"PRId64" new %"PRId64 |