From 5f785de588735306ec4d7c875caf9d28481c8b21 Mon Sep 17 00:00:00 2001 From: Fam Zheng Date: Thu, 6 Nov 2014 20:44:36 +0800 Subject: [PATCH] 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: Fam Zheng Signed-off-by: Benjamin LaHaise --- fs/aio.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/fs/aio.c b/fs/aio.c index bfab55607a4d..1b7893ecc296 100644 --- a/fs/aio.c +++ b/fs/aio.c @@ -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. */ - wait_event_interruptible_hrtimeout(ctx->wait, - aio_read_events(ctx, min_nr, nr, event, &ret), until); + 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); if (!ret && signal_pending(current)) ret = -EINTR; -- 2.20.1