Messages in this thread Patch in this message | | | From | Fam Zheng <> | Subject | [PATCH] aio: Skip timer for io_getevents if timeout=0 | Date | Thu, 6 Nov 2014 20:44:36 +0800 |
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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 <famz@redhat.com> --- fs/aio.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/fs/aio.c b/fs/aio.c index 84a7510..7c0b561 100644 --- a/fs/aio.c +++ b/fs/aio.c @@ -1221,8 +1221,12 @@ 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; -- 1.9.3
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