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

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Message-ID: <20091112121604.GC1394@ucw.cz>
Date:	Thu, 12 Nov 2009 13:16:04 +0100
From:	Pavel Machek <pavel@....cz>
To:	"Ma, Ling" <ling.ma@...el.com>
Cc:	"H. Peter Anvin" <hpa@...or.com>, "mingo@...e.hu" <mingo@...e.hu>,
	"tglx@...utronix.de" <tglx@...utronix.de>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH RFC] [X86] performance improvement for memcpy_64.S by
	fast string.

On Mon 2009-11-09 15:24:03, Ma, Ling wrote:
> Hi All
> 
> Today we run our benchmark on Core2 and Sandy Bridge:
> 
> 1. Retrieve result on Core2
> Speedup on Core2
>    Len        Alignement             Speedup
>   1024,       0/ 0:                 0.95x 
>   2048,       0/ 0:                 1.03x 

Well, so you are running cache hot and it is only a win on huge
copies... how common are those?

> Application run through perf
> For (i= 1024; i < 1024 * 16; i = i + 64)
> 	do_memcpy(0, 0, i);

							Pavel

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