linux-kernel - Re: Quad core CPUs loaded at only 50% when running a CPU and mmap intensive multi-threaded task

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Message-Id: <1219664477.8515.54.camel@twins>
Date:	Mon, 25 Aug 2008 13:41:17 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	edwin <edwintorok@...il.com>
Cc:	Ingo Molnar <mingo@...e.hu>, rml@...h9.net,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	"Thomas Gleixner mingo@...hat.com" <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>
Subject: Re: Quad core CPUs loaded at only 50% when running a CPU and mmap
	intensive multi-threaded task

On Mon, 2008-08-25 at 14:00 +0300, edwin wrote:
> Peter Zijlstra wrote:

> > Right - does it make sense to teach clamav about pread() ?
> 
> If it is preferred over mmap, then maybe yes.

I would certainly consider this for small (< 1M?) files. With mmap the
faults and pte overhead aren't free either, and the extra memcpy from
pread() isn't that much.

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