diff options
| -rw-r--r-- | util/aio-posix.c | 21 |
1 files changed, 15 insertions, 6 deletions
diff --git a/util/aio-posix.c b/util/aio-posix.c index 731f3826c0..6cc6256d53 100644 --- a/util/aio-posix.c +++ b/util/aio-posix.c @@ -585,18 +585,16 @@ static bool try_poll_mode(AioContext *ctx, AioHandlerList *ready_list, max_ns = qemu_soonest_timeout(*timeout, ctx->poll_ns); if (max_ns && !ctx->fdmon_ops->need_wait(ctx)) { + /* + * Enable poll mode. It pairs with the poll_set_started() in + * aio_poll() which disables poll mode. + */ poll_set_started(ctx, ready_list, true); if (run_poll_handlers(ctx, ready_list, max_ns, timeout)) { return true; } } - - if (poll_set_started(ctx, ready_list, false)) { - *timeout = 0; - return true; - } - return false; } @@ -657,6 +655,17 @@ bool aio_poll(AioContext *ctx, bool blocking) * system call---a single round of run_poll_handlers_once suffices. */ if (timeout || ctx->fdmon_ops->need_wait(ctx)) { + /* + * Disable poll mode. poll mode should be disabled before the call + * of ctx->fdmon_ops->wait() so that guest's notification can wake + * up IO threads when some work becomes pending. It is essential to + * avoid hangs or unnecessary latency. + */ + if (poll_set_started(ctx, &ready_list, false)) { + timeout = 0; + progress = true; + } + ctx->fdmon_ops->wait(ctx, &ready_list, timeout); } |