lkml.org 
[lkml]   [2017]   [Feb]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [RFC PATCH] x86/CPU/AMD: Bring back Compute Unit ID

* Borislav Petkov <bp@alien8.de> wrote:

> On Thu, Feb 02, 2017 at 01:10:54PM +0100, Borislav Petkov wrote:
> > Now on to run the same thing on a bigger bulldozer.
>
> It looks differently on the bigger box:
>
> before:
>
> Performance counter stats for 'make -s -j17 bzImage' (3 runs):
> 143.807894000 seconds time elapsed ( +- 0.89% )
>
> Performance counter stats for 'make -s -j17 bzImage' (3 runs):
> 147.109189694 seconds time elapsed ( +- 0.49% )

If there's any doubt about the validity of the measurement I'd suggest doing:

perf stat -a --sync --repeat 3 ...

... so that there's no perf overhead and skew from the many processes of a kernel
build workload, plus the --sync should reduce IO related noise.

Or:

perf stat --null --sync --repeat 3 ...

... will only measure elapsed time, but will do that very precisely and with very
little overhead.

Thanks,

Ingo

\
 
 \ /
  Last update: 2017-02-02 17:11    [W:2.210 / U:0.168 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site