Re: Why not build kernel with -O3

From: Pengfei Yuan
Date: Wed Apr 08 2015 - 09:16:41 EST

2015-04-08 20:19 GMT+08:00 Richard Weinberger <richard.weinberger@xxxxxxxxx>:
> On Wed, Apr 8, 2015 at 3:00 AM, Pengfei Yuan <0xcoolypf@xxxxxxxxx> 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.

This is really helpful.
But I can only find very short description for each option from

> 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?

Redis is special among the six applications because it is single-threaded.

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