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Re: [PATCH v2] grep: remove --mmap

From: Paul Eggert
Subject: Re: [PATCH v2] grep: remove --mmap
Date: Mon, 22 Mar 2010 10:08:40 -0700
User-agent: Gnus/5.13 (Gnus v5.13) Emacs/23.1 (gnu/linux)

Paolo Bonzini <address@hidden> writes:

> mmap is a bad idea for sequentially accessed file because it will cause
> a page fault for every read page.

That would not be true if grep used posix_madvise with the
POSIX_MADV_SEQUENTIAL option, right?  Shouldn't this should be tried out
before removing the use of mmap?

I'm raising this issue because, if I recall correctly, I'm the one who
ripped out the madvise use, way back when madvise actually hurt
performance in SunOS 4.1.  It's pretty safe to say that SunOS 4.1
performance bugs are not relevant any more.

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