diff options
| author | Stefan Hajnoczi <stefanha@redhat.com> | 2013-11-26 16:18:01 +0100 |
|---|---|---|
| committer | Stefan Hajnoczi <stefanha@redhat.com> | 2013-12-06 16:53:51 +0100 |
| commit | d3fa923044321b2ccc12bbdedd582d2c49d958aa (patch) | |
| tree | 47145dfcfa7f48ef385c1393a38c3496da8bae71 | |
| parent | 0b06ef3bdd17742ae50c0662d3fe8ed944648890 (diff) | |
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 <alex@alex.org.uk>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
| -rw-r--r-- | aio-posix.c | 5 | ||||
| -rw-r--r-- | aio-win32.c | 5 | ||||
| -rw-r--r-- | tests/test-aio.c | 1 |
3 files changed, 0 insertions, 11 deletions
diff --git a/aio-posix.c b/aio-posix.c index bd06f33c78..f921d4f538 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, diff --git a/aio-win32.c b/aio-win32.c index f9cfbb75ac..23f4e5ba19 100644 --- a/aio-win32.c +++ b/aio-win32.c @@ -161,11 +161,6 @@ bool aio_poll(AioContext *ctx, bool blocking) ctx->walking_handlers--; - /* early return if we only have the aio_notify() fd */ - if (count == 1) { - return progress; - } - /* wait until next event */ while (count > 0) { int ret; diff --git a/tests/test-aio.c b/tests/test-aio.c index c4fe0fc3b7..592721ed3f 100644 --- a/tests/test-aio.c +++ b/tests/test-aio.c @@ -195,7 +195,6 @@ static void test_bh_delete_from_cb(void) g_assert(data1.bh == NULL); g_assert(!aio_poll(ctx, false)); - g_assert(!aio_poll(ctx, true)); } static void test_bh_delete_from_cb_many(void) |