[SlugBug] Web Server High Utilisation

[Neil Shephard]

On 3/11/06, Chris <chris at slugbug.org.uk> wrote:
> Hi
>
> On Sat 11-Mar-2006 at 09:41:20AM +0000, Alan Dawson wrote:
> >
> > free -m
> >              total       used       free     shared    buffers     cached
> > Mem:          2006        795       1210          0         23        127
> > -/+ buffers/cache:        644       1361
> > Swap:         7632         93       7539
> >
> > > MaxClients
> > 150

I've not really followed this thread, but its my understanding that
free -m is perhaps not the best method of assessing free memory as
Linux does not flush memory.

There is some information on here (although I admit I've not read it
all in detail, but the main point that I took from it is under sectio
3.8 where it indicates that swapping out and discarding pages occurs
when available memory for new process's becomes low.

http://www.linuxhq.com/guides/TLK/mm/memory.html

In particular the line....

"So long as the number of free pages in the system remains above
free_pages_high, the kernel swap daemon does nothing" suggests that
free -m is perhaps not completely accurate for assessing what process'
are using memory.


You could try 'ps' instead with a few flags...

ps -FA | grep 'apache'

(or you could use the -C [cmdlist] flag instead of A, see man ps for more info)

to get a better assesment.

If I'm completely of the mark then someone please do correct me, and
no ill intentions meant.

HTH's

Neil
--
"A wide screen just makes a bad film twice as bad." - Samuel Goldwyn

Email - nshephard at gmail.com / neilshep at cyllene.uwa.edu.au
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