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Re: [PATCH] Don't use SSE4_2 instructions on Intel Silvermont Micro Architecture.
- From: "Carlos O'Donell" <carlos at redhat dot com>
- To: OndÅej BÃlka <neleai at seznam dot cz>
- Cc: Andi Kleen <andi at firstfloor dot org>, Dmitrieva Liubov <liubov dot dmitrieva at gmail dot com>, "H.J. Lu" <hjl dot tools at gmail dot com>, GNU C Library <libc-alpha at sourceware dot org>
- Date: Thu, 20 Jun 2013 21:14:12 -0400
- Subject: Re: [PATCH] Don't use SSE4_2 instructions on Intel Silvermont Micro Architecture.
- References: <CAHjhQ93zmP525hqW-2RnHBREc_949XLnm7sE-CSv3Nj8PQgUig at mail dot gmail dot com> <CAMe9rOqT31AFq1S3V0Krh2CZnHu=FiyXqhg840fimRtfU4_hXQ at mail dot gmail dot com> <20130618064910 dot GA19972 at domone dot kolej dot mff dot cuni dot cz> <CAHjhQ90Fc0kdZfQrUwLwpKbz2va4X9rzf1EkGD-s-RH-iF7guQ at mail dot gmail dot com> <CAHjhQ92qfjdKZthqAwxCVuCnLqDr2stdEbQpne5rKhzJPeN_cQ at mail dot gmail dot com> <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>
On 06/20/2013 09:24 PM, OndÅej BÃlka wrote:
> On Thu, Jun 20, 2013 at 10:54:34AM -0400, Carlos O'Donell wrote:
>> On 06/20/2013 11:17 AM, OndÅej BÃlka wrote:
>>> On Thu, Jun 20, 2013 at 09:46:13AM -0400, Carlos O'Donell wrote:
>>>> On 06/20/2013 09:10 AM, Dmitrieva Liubov wrote:
>>>>> What benchmarks do you mean? string/test-str** unit tests?
>>>>
>>>> I mean the new glibc microbenchmark suite :-)
>>>>
>>
>>> What you have is currently nowhere near of state where you can get
>>> usable results by it. It has five major flaws that i wrote earlier and
>>> any of them is enough to have paper immidiately rejected.
>>
>> Please help us make the microbenchmark better.
>>
> Already tried and will not make same mistake again. Making it better is
> simple, run it and check if outputs make sense. For two months a
> performance of several functions was 100 times faster than it shoud be.
> I do not have any confidence in benchmarks where you do not do such
> basic stuff.
I'm a bit confused, if there was a defect in the benchmark did
you file a bug or post a patch to fix it? What is the mistake
that was made?
>> Until then it's what I'm going to use to determine if Dmitrieva's
>> patch makes performance objectively faster.
>>
> You said that you want performance objectively faster. A definition of objective is:
>
> Condition in the realm of sensible experience independent of individual
> thought and perceptible by all observer.
>
> To see if this is a case I added Andi. Andi, could you browse sources
> and tell if you think that benchtests are adequate to measure
> performance?
I'd love to have Andi review the bench tests and give feedback,
including filing bugs, or helping us make them better.
In my LFCS2013 talk I came out and directly asked for people
with performance measurement experience to help glibc.
Surely the implementation can't offend you so much that you
aren't willing to help us make it better? :-)
Cheers,
Carlos.