From: Stefan Hajnoczi <stefanha@redhat.com>
To: Yaowei Bai <baiyaowei@cmss.chinamobile.com>
Cc: famz@redhat.com, jcody@redhat.com, kwolf@redhat.com,
mreitz@redhat.com, qemu-block@nongnu.org, qemu-devel@nongnu.org,
yjs-kernel@cmss.chinamobile.com
Subject: Re: [Qemu-devel] [PATCH 2/2] aio: improve aio_poll performance by checking epoll only once
Date: Wed, 14 Sep 2016 17:40:17 +0100 [thread overview]
Message-ID: <20160914164017.GR16438@stefanha-x1.localdomain> (raw)
In-Reply-To: <1473851019-7005-3-git-send-email-baiyaowei@cmss.chinamobile.com>
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On Wed, Sep 14, 2016 at 07:03:39AM -0400, Yaowei Bai wrote:
> As epoll whether enabled or not is a global setting, we can just
> check it only once rather than checking it with every node iteration.
> Through this we can avoid a lot of checks when epoll is not enabled.
>
> Signed-off-by: Yaowei Bai <baiyaowei@cmss.chinamobile.com>
> Reviewed-by: Xiubo Li <lixiubo@cmss.chinamobile.com>
> ---
> aio-posix.c | 12 +++++++-----
> 1 file changed, 7 insertions(+), 5 deletions(-)
The commit message says "improve aio_poll performance" but no benchmark
results were provided. Therefore I can't take this patch as a
performance optimization. I'm still happy to merge the patch since it
makes the if statement simpler but I'll rename it to "aio-posix: avoid
unnecessary aio_epoll_enabled() calls".
I don't think this patch gives a measurable performance improvement. If
you believe otherwise, please post benchmark results. Please let me
know what you think.
Stefan
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next prev parent reply other threads:[~2016-09-14 16:40 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-14 11:03 [Qemu-devel] [PATCH 0/2] improve aio_poll performance Yaowei Bai
2016-09-14 11:03 ` [Qemu-devel] [PATCH 1/2] block: mirror: fix wrong comment of mirror_start Yaowei Bai
2016-09-14 17:04 ` Eric Blake
2016-09-14 11:03 ` [Qemu-devel] [PATCH 2/2] aio: improve aio_poll performance by checking epoll only once Yaowei Bai
2016-09-14 16:40 ` Stefan Hajnoczi [this message]
2016-09-18 1:32 ` Yaowei Bai
2016-09-19 15:36 ` [Qemu-devel] [PATCH 0/2] improve aio_poll performance Stefan Hajnoczi
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