From owner-freebsd-performance@FreeBSD.ORG  Tue Jan  3 08:46:59 2012
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Date: Tue, 3 Jan 2012 09:34:54 +0100
From: Marc Olzheim <marcolz@stack.nl>
To: Garrett Cooper <yanegomi@gmail.com>
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Cc: freebsd-performance@freebsd.org, Dieter BSD <dieterbsd@engineer.com>
Subject: Re: cmp(1) has a bottleneck, but where?
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On Tue, Jan 03, 2012 at 12:21:10AM -0800, Garrett Cooper wrote:
>     The file is 3.0GB in size. Look at all those page faults though!
> Thanks!
> -Garrett

=46rom usr.bin/cmp/c_regular.c:

#define MMAP_CHUNK (8*1024*1024)
=2E..
for (..) {
	mmap() chunk of size MMAP_CHUNK.
	compare
	munmap()k
}

That 8 MB chunk size sounds like a bad plan to me. I can imagine
something needed to be done to compare files larger than X GB on a 32bit
system, but 8MB is pretty small...

Marc

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