Re: Simple kernel question

[David Talkington <dtalk prairienet org>]

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John Aldrich wrote:

>> According to Linus, 2.4 kernels should have a 2:1 ratio of swap:RAM.
>> If removing the swap file will bring you below that, I'd leave it.
>>
> <personal belief> I'd say
>256 megs of swap *should* be sufficient for most things, depending on how
>memory-intensive you're going to get. However, on a laptop, I doubt you're
>serving up 2,000 web pages a second or anything similarly memory-intensive!
>;-) </personal belief>

error: <personal belief>: command not found

Ted T'so spoke at length about this at Usenix.  2.4 kernels use swap
in a way that may not be intuitive (and which surprised me).  Roughly
an amount of swap space equivalent to the amount of RAM is used for
what is essentially a mirror of your physical RAM.  Much of your RAM
is swapped out during idle cycles, even if it doesn't need to be.
This makes it a nearly instantaneous operation to purge RAM if needed
for new processes, since the information is already in swap, thus
greatly increasing system response time under some circumstances.
Ergo, if you have 256MB of RAM and 256MB of swap, you're not going to
be able to use swap space efficiently, since there's not room to
shuffle.

So 2:1 it is, personal beliefs notwithstanding.  =)

- -d

- -- 
David Talkington
http://www.spotnet.org

PGP key: http://www.prairienet.org/~dtalk/dt000823.asc

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