From: | "Arjen van der Meijden" <acm(at)tweakers(dot)net> |
---|---|
To: | "'Matthew Hixson'" <hixson(at)poindextrose(dot)org>, <pgsql-performance(at)postgresql(dot)org> |
Subject: | Re: Memory question |
Date: | 2003-06-27 20:55:40 |
Message-ID: | 004b01c33cee$7e6b2560$3ac15e91@acm |
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Lists: | pgsql-performance |
> 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
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