Re: memory usage

On Sunday 07 May 2006 19:43, Michal Mertl wrote:
Jonathan Horne wrote:
On Sunday 07 May 2006 12:09, Jonathan Horne wrote:
i have a server that has 2GB ram, recently upgraded from 1GB ram. it
runs apache2.0 with php5, sendmail with spamass-milter, dovecot,
mysql5.0, cacti, and a couple other small things (like snmp, my bx irc
shell, etc).

when ever i look at the memory usage (via phpsysinfo, or cacti graphs),
its nearly always showing less than 100mb of ram available. top shows
several perls (probably spamassassin), 8 or so httpds (typical), but
that would probably only account for (a liberal guess) 500-600 mb of
ram.

is there a good way to find out where this bottomless ram funnel leads
to? or, should this behavior just be considered typical?

thanks,
jonathan

update...

i just upgraded to the new phpsysinfo rc2, and it shows more detailed
information about what the memory usage is doing. it shows that 1.57GB
is being used by buffers. what is the significance of 1.57GB of memory
being used by 'buffers'?

I would expect a question like this is somewhere in the FAQ.

It is typical that you only see a couple of hundred kilobytes of free
memory on a (at least a little used) FreeBSD system. The system
allocates 'physical' memory as needed (as long as there is some free)
and only when there is no free memory, it starts to reuse some of the
'almost' free memory. 'Almost' free memory is mainly disk cache (your
buffers).

This is nothing to worry about. You can see there is a memory shortage
when there is some swapping during normal workload (in top there appears
"kb in/out" on the swap line). It is neither anything to worry about
when you have some swap space used - FreeBSD is rather aggresively
copying parts of memory to swap when it feels to. As long as it doesn't
need to use the data in the swap often it's an optimization - even disk
cache is better usage of your memory then inactive parts of your
programs' memory.

Michal

well, i guess my system's top confirms what you say:

Swap: 4071M Total, 4071M Free

and, i wasnt experiencing any lack in performance, i was just curious. but i
admit that i must be forgiven for almost doubting!

thanks again,
jonathan
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