[ILUG] swap limit in 2.2

[Scanlan, Brian (5188)]

Back in my Sun tech support days(*sob*) I remember coming across 
a document which was arguing against the allocation of 
"just in case all our apps blow up and at the same time a user 
with a 1gb mailspool opens starts up pine" swap partitions. 

To manage a larger partition, Solaris had to do more work. 
I think the document was written around Solaris 2.5.1 days. It pretty much
just warned against creating pointlessly big swap areas. The problem
of OOM can be dealt with my resource limits.

So, complicating the "How much memory and swap should I buy" problem
was added the clause "How much performance degradation is acceptable
for a just in case situation" - The degradation wasn't loads, and
is probably long since a problem in the land of Solaris. 

Anyway, something to consider - I couldn't find anything about this
on google about Linux. Anybody got a spare machine with 2gb
disk to do some benchmarks? :)
See if a larger swap space on a machine serving web pages causes a
degradation at all...

Brian.

-----Original Message-----
From: Wesley Darlington [mailto:wesley at blackstar.co.uk]
Sent: 10 November 2000 12:18
To: ilug at linux.ie
Subject: Re: [ILUG] swap limit in 2.2


Hi,

On Fri, Nov 10, 2000 at 10:48:39AM +0000, Donncha O Caoimh wrote:
> I know the swap-space limit of 128MB has been removed since the standard
> kernel became 2.2.x, but does anyone know if 2.2 will support a swap
> space of up to 1GB? 
> The machine I'm thinking of has 2GB RAM and plenty of HD space..
> 'Course, if it does start swapping Apache is going to suffer badly, but
> it beats OOM!

I don't know about more than 2GB of swap, but, here's top's top from
a similarly endowed machine...

 12:16pm  up 125 days,  6:45,  1 user,  load average: 3.19, 3.00, 2.95
202 processes: 197 sleeping, 4 running, 1 zombie, 0 stopped
CPU states:  0.0% user,  0.0% system,  0.0% nice,  0.1% idle
Mem:  2010080K av, 2006880K used,   3200K free,   6060K shrd, 535920K buff
Swap: 2097136K av,   5000K used, 2092136K free                1157648K
cached

Note the swap figure. :-)

Wesley.

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