From d3fa923044321b2ccc12bbdedd582d2c49d958aa Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Tue, 26 Nov 2013 16:18:01 +0100 Subject: aio: make aio_poll(ctx, true) block with no fds This patch drops a special case where aio_poll(ctx, true) returns false instead of blocking if no file descriptors are waiting on I/O. Now it is possible to block in aio_poll() to wait for aio_notify(). This change eliminates busy waiting. bdrv_drain_all() used to rely on busy waiting to completed throttled I/O requests but this is no longer required so we can simplify aio_poll(). Note that aio_poll() still returns false when aio_notify() was used. In other words, stopping a blocking aio_poll() wait is not considered making progress. Adjust test-aio /aio/bh/callback-delete/one which assumed aio_poll(ctx, true) would immediately return false instead of blocking. Reviewed-by: Alex Bligh Signed-off-by: Stefan Hajnoczi --- aio-posix.c | 5 ----- 1 file changed, 5 deletions(-) (limited to 'aio-posix.c') diff --git a/aio-posix.c b/aio-posix.c index bd06f33..f921d4f 100644 --- a/aio-posix.c +++ b/aio-posix.c @@ -217,11 +217,6 @@ bool aio_poll(AioContext *ctx, bool blocking) ctx->walking_handlers--; - /* early return if we only have the aio_notify() fd */ - if (ctx->pollfds->len == 1) { - return progress; - } - /* wait until next event */ ret = qemu_poll_ns((GPollFD *)ctx->pollfds->data, ctx->pollfds->len, -- cgit v1.1