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From: Austin S Hemmelgarn <ahferroin7@gmail.com>
To: Richard Weinberger <richard.weinberger@gmail.com>,
	Pengfei Yuan <0xcoolypf@gmail.com>
Cc: Mike Galbraith <umgwanakikbuti@gmail.com>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: Why not build kernel with -O3
Date: Wed, 08 Apr 2015 08:49:14 -0400	[thread overview]
Message-ID: <552523CA.8040106@gmail.com> (raw)
In-Reply-To: <CAFLxGvzZuddx=GA5HTZzJb_=_6U9RRSDS-iRoer7u8T8p8VrmA@mail.gmail.com>

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On 2015-04-08 08:19, Richard Weinberger wrote:
> On Wed, Apr 8, 2015 at 3:00 AM, Pengfei Yuan <0xcoolypf@gmail.com> wrote:
>> Could you please provide some examples that I can investigate?
>> Thanks!
>
> It would be awesome if you could find out which gcc optimizations
> cause the speed up.
> "gcc -c -Q -O3 --help=optimizers" will help you.
>
> Please also double check your results.
> You need do to multiple runs, etc...
> Especially the redis speed up looks odd. Does redis really spend that much time
> in the kernel?
>
My guess would be that much of the speed up is actually related to 
context switch handling and the scheduling/statistics related code.


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  reply	other threads:[~2015-04-08 12:49 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 [this message]
2015-04-08 13:16             ` Pengfei Yuan
2015-04-08 13:21               ` Richard Weinberger
2015-04-27 20:37 ` Pavel Machek

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