lkml.org 
[lkml]   [2015]   [Oct]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH v2 32/36] x86/entry: Micro-optimize compat fast syscall arg fetch
On Fri, Oct 9, 2015 at 12:32 AM, Ingo Molnar <mingo@kernel.org> wrote:
>
> * Andy Lutomirski <luto@kernel.org> wrote:
>
>> we're following a 32-bit pointer, and the uaccess code isn't smart
>> enough to figure out that the access_ok check isn't needed.
>>
>> This saves about three cycles on a cache-hot fast syscall.
>
> Another request: could you please stick the benchmarking code of the various x86
> system call variants into 'perf bench' - under tools/perf/bench/, so that
> measurements can be done on more hardware and can be reproduced easily?
>
> I'd suggest we dedicate an entirely new benchmark family to it: 'perf bench x86'
> and then have:
>
> perf bench x86 syscall vdso
> perf bench x86 syscall int80
> perf bench x86 syscall vdso-compat

I'll play with this. I'm not too familiar with the perf bench stuff.

--Andy


\
 
 \ /
  Last update: 2015-10-09 21:41    [W:0.916 / U:0.056 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site