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Re: [PATCH] Don't use SSE4_2 instructions on Intel Silvermont Micro Architecture.\
- From: Siddhesh Poyarekar <siddhesh dot poyarekar at gmail dot com>
- To: "Carlos O'Donell" <carlos at redhat dot com>
- Cc: Ondřej Bílka <neleai at seznam dot cz>, Liubov Dmitrieva <liubov dot dmitrieva at gmail dot com>, Andi Kleen <andi at firstfloor dot org>, "H.J. Lu" <hjl dot tools at gmail dot com>, GNU C Library <libc-alpha at sourceware dot org>
- Date: Mon, 1 Jul 2013 07:45:30 +0530
- Subject: Re: [PATCH] Don't use SSE4_2 instructions on Intel Silvermont Micro Architecture.\
- References: <51C23583 dot 1070307 at redhat dot com> <CAHjhQ93vWnCiVVU9MPoGptjQtn2J2PCDT2B7ZfXiKt+Cv_Rh_w at mail dot gmail dot com> <51C307A5 dot 7030608 at redhat dot com> <20130620151711 dot GA4891 at domone dot kolej dot mff dot cuni dot cz> <51C317AA dot 6080502 at redhat dot com> <20130621012427 dot GA4574 at domone dot kolej dot mff dot cuni dot cz> <CAAHN_R1HXyy0i25rtYKJ4Zox5u0R57xKbZDq=ZNf0BVm=7biMw at mail dot gmail dot com> <20130621135110 dot GB7973 at domone dot kolej dot mff dot cuni dot cz> <CAHjhQ921kXhi3hfqkHW_5pdYY2QYf6pzQ8OLondc6JJjj++4kQ at mail dot gmail dot com> <51CC602F dot 1010406 at redhat dot com> <20130630195200 dot GA5087 at domone dot homenet dot telecomitalia dot it> <51D09463 dot 7010207 at redhat dot com>
On 1 July 2013 01:56, Carlos O'Donell <carlos@redhat.com> wrote:
>> 1. You use only 32 element sample. Can you be sure that this sample is
>> big enough to be relevant?
>>
>> 2. You take minimum of these samples. Please explain how this is related
>> to real performance.
>>
>> 3. You call this code in loop with same argmuments. Please explain why
>> real world usage cases are close enough that we can observe same
>> behaviour in real world.
Please refer to the archives for answers to those questions.
>> Unless you can satisfactory answer these questions you did not prove
>> anything about performance only got some numbers that are loosely
>> related to it.
>
> Thanks for the review. Could you please start a new thread and CC
> Siddhehs whose the most well versed in this code? Your questions
> are valid questions, and I hope that their discussion leads to a
> better microbenchmark.
These discussions have happened earlier and we have simply been going
around in circles with it. I don't see any point in continuing this
discussion without any constructive code to move the discussion
forward. I will work on improving the string benchmarks in the 2.19
cycle and we can then discuss those patches.
Siddhesh
--
http://siddhesh.in