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From: Folkert van Heusden <folkert@vanheusden.com>
To: Arjan van de Ven <arjan@infradead.org>
Cc: "Robert P. J. Day" <rpjday@mindspring.com>,
	Denis Vlasenko <vda.linux@googlemail.com>,
	Linux kernel mailing list <linux-kernel@vger.kernel.org>
Subject: Re: replace "memset(...,0,PAGE_SIZE)" calls with "clear_page()"?
Date: Sun, 31 Dec 2006 14:39:02 +0100	[thread overview]
Message-ID: <20061231133902.GA13521@vanheusden.com> (raw)
In-Reply-To: <1167518748.20929.578.camel@laptopd505.fenrus.org>

> > 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.

What about an if (adress & 15) { memset } else { sse stuff }
or is that too obvious? :-)

> 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)


Folkert van Heusden

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  parent reply	other threads:[~2006-12-31 13:39 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-12-29  6:16 replace "memset(...,0,PAGE_SIZE)" calls with "clear_page()"? Robert P. J. Day
2006-12-30 20:49 ` Denis Vlasenko
2006-12-30 22:08   ` Robert P. J. Day
2006-12-30 22:40     ` Denis Vlasenko
2007-01-03  6:23       ` dean gaudet
2006-12-30 22:45     ` Arjan van de Ven
2006-12-30 23:04       ` Robert P. J. Day
2006-12-31 18:39         ` Paul Mundt
2006-12-31 19:04           ` Robert P. J. Day
2007-01-01  1:59             ` Folkert van Heusden
2007-01-01  8:33               ` Robert P. J. Day
2007-01-01 10:14                 ` Arjan van de Ven
2007-01-01 10:27                   ` Robert P. J. Day
2007-01-01 19:05                     ` Dave Jones
2007-01-01  8:42               ` Paul Mundt
2007-01-01 17:09                 ` Randy Dunlap
2006-12-31 13:39       ` Folkert van Heusden [this message]
2006-12-31 13:45         ` Arjan van de Ven
2006-12-31 16:39           ` Robert P. J. Day
2006-12-31 17:43             ` Arjan van de Ven
2007-01-03 13:20               ` Robert P. J. Day

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