From: | Neil Conway <nconway(at)klamath(dot)dyndns(dot)org> |
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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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Lists: | pgsql-general |
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
--
Neil Conway <neilconway(at)home(dot)com>
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Violence is to dictatorship as propaganda is to democracy.
-- Noam Chomsky
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