On 25 Sep 2013, at 13:15, Stefan Hajnoczi wrote: > 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. > > Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com>
Signed-off-by: Alex Bligh <a...@alex.org.uk> (if I meant 'Reviewed-By:' please change it!) > --- > aio-posix.c | 5 ----- > aio-win32.c | 5 ----- > tests/test-aio.c | 1 - > 3 files changed, 11 deletions(-) > > 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, > diff --git a/aio-win32.c b/aio-win32.c > index f9cfbb7..23f4e5b 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 c4fe0fc..592721e 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) > -- > 1.8.3.1 > > > -- Alex Bligh