Re: -F option, RAM usage, more...

From: Neil Conway <nconway(at)klamath(dot)dyndns(dot)org>
To: pgsql-general(at)hub(dot)org
Subject: Re: -F option, RAM usage, more...
Date: 2000-10-04 20:24:02
Message-ID: 20001004162402.A19300@klamath.dyndns.org
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On Wed, Oct 04, 2000 at 02:09:47PM -0400, Mike Biamonte wrote:
> I understand from the docs that -F ".. prevents fsync()'s from
> flushing to disk after every transaction.." and that this boosts
> performance because RAM accesses are far faster than disk accesses. I
> have also seen some impressive stats regarding the degree of this
> performance boost.

Correct me if I'm wrong, but I believe that when you specify '-F', it
allows the filesystem to buffer I/O operations, performing several
operations once after another. This is much faster than with fsync(),
where the disk heads have to be moved frequently. Also, allowing the
I/O subsystem to buffer some data will speed subsequent accesses of it,
until the buffer is flushed.

HTH,

Neil

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Neil Conway <neilconway(at)home(dot)com>
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