linux-kernel - RE: [PATCH RFC] [x86] Optimize copy-page by reducing impact from HW prefetch

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Date:	Tue, 28 Jun 2011 23:23:52 +0800
From:	"Ma, Ling" <ling.ma@...el.com>
To:	Ingo Molnar <mingo@...e.hu>, Andi Kleen <andi@...stfloor.org>
CC:	"hpa@...or.com" <hpa@...or.com>,
	"tglx@...utronix.de" <tglx@...utronix.de>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH RFC] [x86] Optimize copy-page by reducing impact from HW
 prefetch

Hi Ingo
 
> Ling, mind double checking which one is the faster/better one on SNB,
> in cold-cache and hot-cache situations, copy_page or copy_page_c?
Copy_page_c 
on hot-cache copy_page_c on SNB combines data to 128bit (processor limit 128bit/cycle for write) after startup latency
so it is faster than copy_page which provides 64bit/cycle for write.

on cold-cache copy_page_c doesn't use prefetch, which uses prfetch according to copy size,
so copy_page function is better. 

Thanks
Ling

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