[RFC] Porting string performance tests into benchtests

[David Miller]

From: Siddhesh Poyarekar <siddhesh@redhat.com>
Date: Fri, 5 Apr 2013 10:08:01 +0530

> On Wed, Apr 03, 2013 at 11:40:42PM -0400, David Miller wrote:
>> I really want to see on the cpu cycle level whether the changes I make
>> to the pre-loop and post-loop code make any difference.
>> 
>> And on sparc chips I don't have the issues that can make the cpu cycle
>> counter inaccurate or less usable as a timing mechanism.
> 
> I realized that my understanding of CLOCK_PROCESS_CPUTIME_ID was
> flawed.  While it is described as 'cpu time consumed by the process',
> it seems to still be sufficiently impacted by system load.  Maybe the
> cost of switching gets added as well, I'm not sure.  What I'll do now
> is see if HP_TIMING gives reasonably consistent results in the same
> conditions as CLOCK_PROCESS_CPUTIME_ID does and if it does, I'll
> modify the benchmark code to use it if available.  If not, we fall
> back to CLOCK_PROCESS_CPUTIME_ID.
> 
> Does that sound like a good plan?

Yes.