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To: Mike Silbersack <silby@silby.com>
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From: des@des.no (Dag-Erling =?iso-8859-1?q?Sm=F8rgrav?=)
Date: Sun, 26 Oct 2003 12:06:49 +0100
In-Reply-To: <20031026065621.GA21546@VARK.homeunix.com> (David Schultz's
 message of "Sat, 25 Oct 2003 23:56:21 -0700")
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cc: freebsd-hackers@FreeBSD.ORG
cc: Q <q_dolan@yahoo.com.au>
cc: Kris Kennaway <kris@obsecurity.org>
Subject: Re: Some mmap observations compared to Linux 2.6/OpenBSD
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David Schultz <das@FreeBSD.ORG> writes:
> I'm not particularly ``familiar'' with postgres, but I did some
> performance tests on it a little while ago.  Grepping through one
> of the traces just now, I found that database system made 139
> calls to mmap(), and the maximum number of regions mapped at any
> given time was 39.[1]

PostgreSQL doesn't mmap its data.  The mmap() calls you saw were from
malloc().  The only place PostgreSQL calls mmap() directly is for IPC
in the QNX port (because QNX apparently doesn't have SysV IPC).

DES
--=20
Dag-Erling Sm=F8rgrav - des@des.no