From: Arjen van der Meijden <acm@tweakers.net>
To: 'Matthew Hixson' <hixson@poindextrose.org>
To: pgsql-performance@postgresql.org
Subject: Re: Memory question
Date: Fri, 27 Jun 2003 22:55:40 +0200
Message-ID: <004b01c33cee$7e6b2560$3ac15e91@acm> (raw)
In-Reply-To: <30A40B16-A8DE-11D7-81EC-000393669C1A@poindextrose.org>
> I've heard that too, but it doesn't seem to make much sense
> to me. If
> you get to the point where your machine is _needing_ 2GB of swap then
> something has gone horribly wrong (or you just need more RAM in the
> machine) and it will just crawl until the kernel kills off whatever
> process causes the swap space to be exceeded. Seems to me that you
> should only have that much swap if you can't afford more RAM
> or you've
> tapped out your machine's capacity, and your application needs that
> much memory.
> -M@
I've heard the same, the reason behind it was that there needs to be
one-to-one copy of the memory to be able to swap out everything and to
have a gain in the total "memory", you'd need twice as much swap as
memory to have a doubling of your memory.
But afaik this behaviour has been adjusted since the 2.4.5 kernel and
isn't a real issue anymore.
Please keep in mind that I'm no expert at all on linux, so if you want
to be sure, you'd better mail to the kernel-mailinglist orso :)
Anyway, I manage a few machines with 1GB++ memory and none of them has
more than 1G of swap and none of them uses that swap for more than a few
MB unless something was terribly wrong, so the actual 'risk' probably
doesn't have a high chance to occur.
Arjen
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-performance@postgresql.org
Cc: acm@tweakers.net, hixson@poindextrose.org
Subject: Re: Memory question
In-Reply-To: <004b01c33cee$7e6b2560$3ac15e91@acm>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox