From: Pavel Machek <pavel@ucw.cz>
To: Pengfei Yuan <0xcoolypf@gmail.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: Why not build kernel with -O3
Date: Mon, 27 Apr 2015 22:37:18 +0200 [thread overview]
Message-ID: <20150427203718.GG29351@xo-6d-61-c0.localdomain> (raw)
In-Reply-To: <CACmZjJK8oLLFWBzUZpRTVrTycu8JDfd+hg6bBuxi-a8U6Hk_1A@mail.gmail.com>
Hi!
> I have conducted some experiments to compare kernels built with -O2
> and -O3. Here are the results:
>
> Application Performance O2 Performance O3 Improvement
> Apache 127814.14 req/s 130321.24 req/s 1.96%
> Nginx 537589.08 req/s 556723.32 req/s 3.56%
> MySQL 70661.38 tx/s 71008.47 tx/s 0.49%
> PostgreSQL 79763.39 tx/s 79535.59 tx/s -0.29%
> Redis 352547.47 op/s 405417.24 op/s 15.0%
> Memcached 844439.14 op/s 845321.79 op/s 0.10%
>
> Geomean: +3.34%
>
> Experiment environment: Linux 3.19.3, GCC 4.9.3 prerelease, Core-i7
> 4770, 32G RAM, 10GbE
>
> LMbench microbenchmark also shows reduction in various latencies, as
> well as increase of throughputs.
What is the size difference with -O3?
Do you have mostly-userspace benchmark? (kernel build?) -O3 could hurt there
if it produces bigger code..
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
prev parent reply other threads:[~2015-04-27 20:37 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-07 3:37 Why not build kernel with -O3 Pengfei Yuan
2015-04-07 6:43 ` Mike Galbraith
2015-04-07 7:07 ` Boaz Harrosh
2015-04-07 8:29 ` Mike Galbraith
2015-04-07 7:56 ` Pengfei Yuan
2015-04-07 10:09 ` Mike Galbraith
2015-04-07 18:05 ` Austin S Hemmelgarn
2015-04-08 1:00 ` Pengfei Yuan
2015-04-08 12:06 ` Austin S Hemmelgarn
2015-04-08 12:57 ` One Thousand Gnomes
2015-04-08 13:19 ` Pengfei Yuan
2015-04-08 13:53 ` Austin S Hemmelgarn
2015-04-08 12:19 ` Richard Weinberger
2015-04-08 12:49 ` Austin S Hemmelgarn
2015-04-08 13:16 ` Pengfei Yuan
2015-04-08 13:21 ` Richard Weinberger
2015-04-27 20:37 ` Pavel Machek [this message]
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