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Date:      Mon, 16 Aug 2004 01:39:53 -0400
From:      "Mark W. Krentel" <krentel@dreamscape.com>
To:        des@des.no, cvs-all@FreeBSD.org
Cc:        alc@FreeBSD.org
Subject:   Re: cvs commit: src/sys/vm vm_map.c vm_map.h
Message-ID:  <200408160539.i7G5drJE018193@blue.mwk.domain>

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> Great!  I've been meaning to do this for a while, but the complexity
> was a bit beyond me.  This should greatly increase pipe performance,
> by the way, because pipe buffers are allocated from a single vm_map,
> which accumulates many more entries and much more fragmentation than
> (probably) most other maps in the kernel.

If you (or anyone else) have a real-world application that runs
measurably better with the new vm_map_findspace() algorithm, I'd
love to hear about it, especially if you have numbers.  Probably on
-hackers or something.

I can write a one-page C program that mmap()'s many pages with holes
between them that is a factor of 50-100 faster with the new algorithm
where "many" is around 10,000.  But it's a very artificial micro-
benchmark.

--Mark



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