Date: Thu, 11 Dec 2003 00:01:20 -0500 (EST) From: Robert Watson <rwatson@freebsd.org> To: Dan Nelson <dnelson@allantgroup.com> Cc: freebsd-hackers@freebsd.org Subject: Re: adding more ram Message-ID: <Pine.NEB.3.96L.1031210235954.76718E-100000@fledge.watson.org> In-Reply-To: <20031210063845.GG2435@dan.emsphone.com>
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On Wed, 10 Dec 2003, Dan Nelson wrote: > In the last episode (Dec 10), nbari@unixmexico.com said: > > I have a server with 1GB of RAM and a swap partition of 2GB i will > > upgrade the memory server to 2GB so my questions are: > > > > should i fix the swap partition to have now 4GB of space ? > > Depends. Have you ever used up that 2gb of swap? If not, you'll > probably never consume 4gb either :) If this is a database server, or > something similar where a few processes allocate large amounts of > memory, you don't need much swap anyway, since if any of those processes > actually has to swap, you end up thrashing the system as it tries to > swap 500mb processes in and out of memory. I really can't think of a > system that would still perform well with 2 or 3GB of process space in > swap. At the 2gb RAM point, you usually have a system where any > swapping == bad news. Actually, the thing I use swap for most now is to make sure I can allocate large temporary file systems without consuming excessive kernel address space. I.e., I'll often create a 512mb swap-backed md device for /tmp, and make sure I have enough swap to fully back it and everything else, even though the chances are I won't touch it in normal operation. I just don't want to run out in the event something does need it... Robert N M Watson FreeBSD Core Team, TrustedBSD Projects robert@fledge.watson.org Senior Research Scientist, McAfee Research
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