Re: [PATCH] Faster strchr implementation.

[Liubov Dmitrieva <liubov dot dmitrieva at gmail dot com>]

I tried the updated version for Haswell, strchr profiler hasn't
completed the tests due to a fail in Makefile.
See the log and the results.


Yes, I saw the graphs for strchr, strrchr, stcmp where it passed
correctly and I agree with your summary thought I see weird draw downs
at some strcmp plots (like strcmp_hsw/results_rand_L3/result.html
(plot #2) and many like this ). How should we interpret draw downs
here?

--
Liubov Dmitrieva
Intel Corporation

On Fri, Aug 9, 2013 at 8:44 PM, OndÅej BÃlka <neleai@seznam.cz> wrote:
> On Fri, Aug 09, 2013 at 06:05:43PM +0400, Liubov Dmitrieva wrote:
>>
> Yes, thanks. I updated with them pages:
>
> http://kam.mff.cuni.cz/~ondra/benchmark_string/strcmp_profile.html
> http://kam.mff.cuni.cz/~ondra/benchmark_string/strchr_profile.html
> http://kam.mff.cuni.cz/~ondra/benchmark_string/strrchr_profile.html
>
> As you can see graphs strcmp is 10% faster on haswell, atom and
> silvermont.
>
> As avx2 implementation goes on haswell it is around 20% faster on large
> inputs, but problem there is that most of time inputs are small. Using
> avx is around 3% slower than strcmp_new on gcc test. One possible cause is
> bigger latency of avx2, it may be worth to add avx2 ifunc.
>
> As strchr is concerned a no_bsf version is still faster on atom and
> silvermont. My implementation win for larger sizes but I pays heavy penalty
> for switching to 64 byte loop while strchr_no_bsf loop is cheap.
>
> A strrchr a new implementation is faster than current ones both
> practically and asymptotically on haswell,atom and silvermont.
>
> As haswell I fixed strchr and strrchr benchmarks to call correct avx2
> implementation. New version is here:
>
> http://kam.mff.cuni.cz/~ondra/benchmark_string/strchr_profile090813.tar.bz2
> http://kam.mff.cuni.cz/~ondra/benchmark_string/strrchr_profile090813.tar.bz2
>
> It was bug in implementation, now fixed.
> They are tested automatically.
>
> --
>
> endothermal recalibration

Attachment: log_strchr_haswell.txt
Description: Text document

Attachment: results_strchr_haswell_with_fail.tar.bz2
Description: BZip2 compressed data

Attachment: results_strrchr_haswell.tar.bz2
Description: BZip2 compressed data