This is the mail archive of the
libc-alpha@sourceware.org
mailing list for the glibc project.
Re: [PATCH] Rename __memcmp_sse4_2 to __memcmp_sse4_1.
- From: Liubov Dmitrieva <liubov dot dmitrieva at gmail dot com>
- To: "H.J. Lu" <hjl dot tools at gmail dot com>
- Cc: Matt Turner <mattst88 at gmail dot com>, Andreas Jaeger <aj at suse dot com>, GNU C Library <libc-alpha at sourceware dot org>
- Date: Thu, 11 Jul 2013 18:07:49 +0400
- Subject: Re: [PATCH] Rename __memcmp_sse4_2 to __memcmp_sse4_1.
- References: <CAMe9rOreowCOEH+6zRaRNk_p9sYe3T2bhwPRbKpybW9cO0BhJA at mail dot gmail dot com> <1373419029-19125-1-git-send-email-mattst88 at gmail dot com> <51DCE51F dot 7000001 at suse dot com> <CAMe9rOqb3_DnhSh0jPh9=suJo5c+WjegxfDh1+1go6pY+7+PLA at mail dot gmail dot com> <CAEdQ38Go4UY=k==nYT_6S86-tsOoxOO=Wn=8_pNk+LkkxSxU_Q at mail dot gmail dot com> <CAMe9rOpgaNgGSdoM5rXdhLT-TqVEJjGMyHgKRP=t+2LrSTpFAA at mail dot gmail dot com> <CAEdQ38FBeyuJpQ1eSHnM5w=8MHD3cfFjgWekkXnRFHO+Aathnw at mail dot gmail dot com> <CAMe9rOompuMMzQm+RX=ejoPMX0uWmXarvSZa_fp-Fi1p_-8o1Q at mail dot gmail dot com>
My Silvermont patch in the latest edition doesn't touch memcmp and
wmemcmp at all because I didn't see good boost from switching SSE42
off for these 2 functions.
Now I see why. There are no SSE42 instruction there. :)
The patch looks good. I will just check performance regressions for Penryn.
--
Liubov
On Wed, Jul 10, 2013 at 10:23 PM, H.J. Lu <hjl.tools@gmail.com> wrote:
> On Wed, Jul 10, 2013 at 11:19 AM, Matt Turner <mattst88@gmail.com> wrote:
>> On Wed, Jul 10, 2013 at 11:16 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
>>> On Wed, Jul 10, 2013 at 10:41 AM, Matt Turner <mattst88@gmail.com> wrote:
>>>> On Wed, Jul 10, 2013 at 8:30 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
>>>>> On Tue, Jul 9, 2013 at 9:37 PM, Andreas Jaeger <aj@suse.com> wrote:
>>>>>> On 07/10/2013 03:17 AM, Matt Turner wrote:
>>>>>>> It uses SSE 4.1 instructions (ptest) but no SSE 4.2 instructions.
>>>>>>
>>>>>> There are two parts to this: It should only run on cpus with those
>>>>>> instructions but we also need to ensure that it gives a better
>>>>>> performance on such cpus. HJ, Matt, please do run performance tests on a
>>>>>> variety of affected cpus to show that this change really helps in all cases,
>>>>>>
>>>>>> Andreas
>>>>>
>>>>> Only Penryn has SSE4.1 without SSE4.2. Liubov, can
>>>>> you compare performance of memcmp-sse4.S vs
>>>>> memcmp-ssse3.S on Penryn?
>>>>
>>>> Is it also the case that this path would now be used on Silvermont?
>>>
>>> It is used on Silvermont since it supports SSE4.2
>>>
>>> --
>>> H.J.
>>
>> To confirm, setting bit_Slow_SSE4_2 on Silvermont (which we do)
>> wouldn't prevent this path from executing?
>
> I don't think so. Liubov, can you verify it?
>
> --
> H.J.