linux-kernel - RE: [PATCH RFC] [X86] performance improvement for memcpy

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Date:	Thu, 12 Nov 2009 12:49:04 +0800
From:	"Ma, Ling" <ling.ma@...el.com>
To:	Cyrill Gorcunov <gorcunov@...il.com>,
	"H. Peter Anvin" <hpa@...or.com>
CC:	Ingo Molnar <mingo@...e.hu>, Ingo Molnar <mingo@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH RFC] [X86] performance improvement for memcpy_64.S by
 fast 	string.

Hi All
The attachment is latest memcpy.c, please update by 
"cc -o memcpy memcpy.c -O2 -m64".

Thanks
Ling


>-----Original Message-----
>From: Cyrill Gorcunov [mailto:gorcunov@...il.com]
>Sent: 2009年11月12日 12:28
>To: H. Peter Anvin
>Cc: Ma, Ling; Ingo Molnar; Ingo Molnar; Thomas Gleixner; linux-kernel
>Subject: Re: [PATCH RFC] [X86] performance improvement for memcpy_64.S by fast
>string.
>
>On Thu, Nov 12, 2009 at 1:39 AM, H. Peter Anvin <hpa@...or.com> wrote:
>> On 11/11/2009 12:34 PM, Cyrill Gorcunov wrote:
>>>                                               memcpy_orig     memc
>py_new
>>> TPT: Len 1024, alignment  8/ 0:               490             570
>>> TPT: Len 2048, alignment  8/ 0:               826             329
>>> TPT: Len 3072, alignment  8/ 0:               441             464
>>> TPT: Len 4096, alignment  8/ 0:               579             596
>>> TPT: Len 5120, alignment  8/ 0:               723             729
>>> TPT: Len 6144, alignment  8/ 0:               859             861
>>> TPT: Len 7168, alignment  8/ 0:               996             994
>>> TPT: Len 8192, alignment  8/ 0:               1165            1127
>>> TPT: Len 9216, alignment  8/ 0:               1273            1260
>>> TPT: Len 10240, alignment  8/ 0:      1402            1395
>>> TPT: Len 11264, alignment  8/ 0:      1543            1525
>>> TPT: Len 12288, alignment  8/ 0:      1682            1659
>>> TPT: Len 13312, alignment  8/ 0:      1869            1815
>>> TPT: Len 14336, alignment  8/ 0:      1982            1951
>>> TPT: Len 15360, alignment  8/ 0:      2185            2110
>>>
>>> I've run this test a few times and results almost the same,
>>> with alignment 1024, 3072, 4096, 5120, 6144, new version a bit slowly.
>>>
>>
>> Was the result for 2048 consistent (it seems odd in the extreme)... the
>> discrepancy between this result and Ling's results bothers me; perhaps
>> the right answer is to leave the current code for Core2 and use new code
>> (with a lower than 1024 threshold?) for NHM and K8?
>>
>>        -hpa
>>
>
>Hi Peter,
>
>no, results for 2048 is not repeatable (that is why I didn't mention this number
>in a former report).
>
>Test1:
>TPT: Len 2048, alignment  8/ 0:	826	329
>Test2:
>TPT: Len 2048, alignment  8/ 0:	359	329
>Test3:
>TPT: Len 2048, alignment  8/ 0:	306	331
>Test4:
>TPT: Len 2048, alignment  8/ 0:	415	329
>
>I guess this was due to cpu frequency change from 800 to 2.1Ghz since
>I did tests manually
>not using any kind of bash cycle to run the test program.

View attachment "memcpy.c" of type "text/plain" (5495 bytes)