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From: Will Newton <will.newton@linaro.org>
To: "Carlos O'Donell" <carlos@redhat.com>
Cc: "libc-ports@sourceware.org" <libc-ports@sourceware.org>,
	"Patch Tracking" <patches@linaro.org>,
	"Ondřej Bílka" <neleai@seznam.cz>,
	"Siddhesh Poyarekar" <siddhesh@redhat.com>
Subject: Re: [PATCH] sysdeps/arm/armv7/multiarch/memcpy_impl.S: Improve performance.
Date: Mon, 02 Sep 2013 14:18:00 -0000	[thread overview]
Message-ID: <CANu=DmgQgnwR8Wr3VGWp2Y5Zx0AxcS4H=c-m5vrSOjHCN7Hw_Q@mail.gmail.com> (raw)
In-Reply-To: <5220F1F0.80501@redhat.com>

On 30 August 2013 20:26, Carlos O'Donell <carlos@redhat.com> wrote:
> On 08/30/2013 02:48 PM, Will Newton wrote:
>> On 30 August 2013 18:14, Carlos O'Donell <carlos@redhat.com> wrote:
>>
>> Hi Carlos,
>>
>>>>> A small change to the entry to the aligned copy loop improves
>>>>> performance slightly on A9 and A15 cores for certain copies.
>>>>>
>>>>> ports/ChangeLog.arm:
>>>>>
>>>>> 2013-08-07  Will Newton  <will.newton@linaro.org>
>>>>>
>>>>>         * sysdeps/arm/armv7/multiarch/memcpy_impl.S: Tighten check
>>>>>         on entry to aligned copy loop for improved performance.
>>>>> ---
>>>>>  ports/sysdeps/arm/armv7/multiarch/memcpy_impl.S | 4 ++--
>>>>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>>>
>>>> Ping?
>>>
>>> How did you test the performance?
>>>
>>> glibc has a performance microbenchmark, did you use that?
>>
>> No, I used the cortex-strings package developed by Linaro for
>> benchmarking various string functions against one another[1].
>>
>> I haven't checked the glibc benchmarks but I'll look into that. It's
>> quite a specific case that shows the problem so it may not be obvious
>> which one is better however.
>
> If it's not obvious how is someone supposed to review this patch? :-)
>
>> [1] https://launchpad.net/cortex-strings
>
> There are 2 benchmarks. One appears to be dhrystone 2.1, which isn't a string
> test in and of itself which should not be used for benchmarking or changing
> string functions. The other is called "multi" and appears to run some functions
> in a loop and take the time.
>
> e.g.
> http://bazaar.launchpad.net/~linaro-toolchain-dev/cortex-strings/trunk/view/head:/benchmarks/multi/harness.c
>
> I would not call `multi' exhaustive, and while neither is the glibc performance
> benchmark tests the glibc tests have received review from the glibc community
> and are our preferred way of demonstrating performance gains when posting
> performance patches.
>
> I would really really like to see you post the results of running your new
> implementation with this benchmark and show the numbers that claim this is
> faster. Is that possible?

The mailing list server does not seem to accept image attachments so I
have uploaded the performance graph here:

http://people.linaro.org/~will.newton/glibc_memcpy/sizes-memcpy-08-04-2.5.png

-- 
Will Newton
Toolchain Working Group, Linaro

  reply	other threads:[~2013-09-02 14:18 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-08-12  7:55 Will Newton
2013-08-27  7:46 ` Will Newton
2013-08-30 17:14   ` Carlos O'Donell
2013-08-30 18:48     ` Will Newton
2013-08-30 19:26       ` Carlos O'Donell
2013-09-02 14:18         ` Will Newton [this message]
2013-09-03 16:14           ` Carlos O'Donell
     [not found]         ` <CANu=DmhA9QvSe6RS72Db2P=yyjC72fsE8d4QZKHEcNiwqxNMvw@mail.gmail.com>
2013-09-02 14:18           ` benchmark improvements (Was: Re: [PATCH] sysdeps/arm/armv7/multiarch/memcpy_impl.S: Improve performance.) Siddhesh Poyarekar
2013-09-03 13:46             ` Will Newton
2013-09-03 17:48               ` Ondřej Bílka
2013-09-02 19:57           ` [PATCH] sysdeps/arm/armv7/multiarch/memcpy_impl.S: Improve performance Ondřej Bílka
2013-09-03 16:18           ` Carlos O'Donell
2013-09-03 17:37             ` Ondřej Bílka
2013-09-03 17:52               ` Carlos O'Donell
2013-09-03 18:57                 ` Ondřej Bílka
2013-09-03 19:15                   ` Carlos O'Donell
2013-09-04  7:27                     ` Siddhesh Poyarekar
2013-09-04 11:03                       ` Ondřej Bílka
2013-09-04 11:43                         ` Siddhesh Poyarekar
2013-09-04 17:37                         ` Ryan S. Arnold
2013-09-05  8:04                           ` Ondřej Bílka
2013-09-04 15:30                       ` Carlos O'Donell
2013-09-04 17:35                       ` Ryan S. Arnold
2013-09-05 11:07                         ` Ondřej Bílka
2013-09-05 11:54                         ` Joseph S. Myers
2013-09-03 19:34               ` Ryan S. Arnold
2013-09-07 11:55                 ` Ondřej Bílka
2013-09-03 19:31             ` Ryan S. Arnold
2013-09-03 19:54               ` Carlos O'Donell
2013-09-03 20:56                 ` Ryan S. Arnold
2013-09-03 23:29                   ` Ondřej Bílka
2013-09-03 23:31                   ` Carlos O'Donell
2013-09-03 22:27               ` Ondřej Bílka
2013-08-29 23:58 ` Joseph S. Myers
2013-08-30 14:56   ` Will Newton
2013-08-30 15:18     ` Joseph S. Myers
2013-08-30 18:46       ` Will Newton

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