Commit 5f785de5 authored by Fam Zheng's avatar Fam Zheng Committed by Benjamin LaHaise
Browse files

aio: Skip timer for io_getevents if timeout=0 



In this case, it is basically a polling. Let's not involve timer at all
because that would hurt performance for application event loops.

In an arbitrary test I've done, io_getevents syscall elapsed time
reduces from 50000+ nanoseconds to a few hundereds.

Signed-off-by: default avatarFam Zheng <famz@redhat.com>
Signed-off-by: default avatarBenjamin LaHaise <bcrl@kvack.org>
parent e4a0d3e7

fs/aio.c

+6 −2
Original line number Diff line number Diff line
@@ -1253,8 +1253,12 @@ static long read_events(struct kioctx *ctx, long min_nr, long nr, 
	 * the ringbuffer empty. So in practice we should be ok, but it's

	 * something to be aware of when touching this code.

	 */

	if (until.tv64 == 0)

		aio_read_events(ctx, min_nr, nr, event, &ret);

	else

		wait_event_interruptible_hrtimeout(ctx->wait,

			aio_read_events(ctx, min_nr, nr, event, &ret), until);

				aio_read_events(ctx, min_nr, nr, event, &ret),

				until);



	if (!ret && signal_pending(current))

		ret = -EINTR;