[sclug] Dell desktop for 175GBP inc. delivered - offer closes 2/11/2005

[Alex Butcher]

On Thu, 27 Oct 2005, John Stumbles wrote:

> BUT.... I think I need more RAM. `top` shows:
> Mem:    256792k total,   254736k used,     2056k free,      944k buffers
> Swap:   979956k total,   314992k used,   664964k free,    43416k cached
> suggesting that even with 512M I'd still be swapping (and I haven't even got 
> OOo open, let alone multiple users' GUIs running).

Quite possibly, but it could just be stuff that gets swapped out shortly
after being started, and never/rarely gets woken and brought back into RAM
(e.g. cups, apache). Note that you have ~43MB of disc cache, which suggests
that this is already the case.

Probably best to have a look at the output of 'vmstat 1', particularly the
'si' and 'so' columns to determine whether you're actively swapping.

More likely, you're heavily IO-bound. Are you using SCSI or ATA discs? If
ATA, have you enabled DMA (use hdparm to check)? If you're using a 2.6
kernel, have you tried using a different IO scheduler; I'm not convinced
that the default - cfq - is good for anything but busy server loads. I'd
suggest trying the 'deadline' and 'as' schedulers, at least.

<http://www.redhat.com/magazine/008jun05/features/schedulers/>

Also, if you're running 2.6, consider playing with the IO priorities:

<http://akt.sourceforge.net/doc/akt.list.02.html#1.2> [see those highlighted
blue]
<http://www.gelato.unsw.edu.au/IA64wiki/TuningLinux>
<http://lists.freedesktop.org/archives/hal/2005-September/003350.html>

HTH,
Alex.
-- 
Alex Butcher      Brainbench MVP for Internet Security: www.brainbench.com
Bristol, UK                      Need reliable and secure network systems?
PGP/GnuPG ID:0x271fd950                         <http://www.assursys.com/>