linux-kernel - Re: replace "memset(...,0,PAGE_SIZE)" calls with "clear

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Message-Id: <1167518748.20929.578.camel@laptopd505.fenrus.org>
Date:	Sat, 30 Dec 2006 23:45:48 +0100
From:	Arjan van de Ven <arjan@...radead.org>
To:	"Robert P. J. Day" <rpjday@...dspring.com>
Cc:	Denis Vlasenko <vda.linux@...glemail.com>,
	Linux kernel mailing list <linux-kernel@...r.kernel.org>
Subject: Re: replace "memset(...,0,PAGE_SIZE)" calls with "clear_page()"?

> i don't see how that can be true, given that most of the definitions
> of the clear_page() macro are simply invocations of memset().  see for
> yourself:

*MOST*. Not all.
For example an SSE version will at least assume 16 byte alignment, etc
etc.

clear_page() is supposed to be for full real pages only... for example
it allows the architecture to optimize for alignment, cache aliasing etc
etc. (and if there are cpus that get a "clear an entire page"
instruction.... there has been hardware like that in the past, even on
x86, just it's no longer sold afaik)

-- 
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