Hello!,

I try to merge answers from Rob Love and Mark Hahn.

On Wednesday 26 November 2003 20:01, Mark Hahn wrote:
> > 1/ can you explain me what happened in week 47 so cached memory don't get
> > down anymore ? Nothing really changed in this week on the server.
>
> I'm guessing someone did a "find /" or similar, which caused lots of
> dcache/icache entries to be created.  of course, it could also be normal
> cached file pages, stale SHM segments (run ipcs -a), or maybe even
> a big-VM proces that's gotten into some limbo state...
 o no one did a "find /" , however as in any RedHat each night at 4 pm the 
'updatedb' script is launched (even before week 47).
 o for ipcs output I got lots of things but I don't understand it yet I have 
to read some docs on that.

I attach output from '/proc/meminfo' and '/proc/slabinfo' to this mail.

>
> > 2/ how can I know when my server needs more RAM/SWAP, if free memory is
> > always about 0
>
> free memory is WASTED memory - you might as well have not bought it.
> you know you need more memory when you see swapin traffic (NOT swapouts,
> which are normal and in fact good).  swapins are a sign that the kernel
> has either chosen the wrong pages to swap out, or is needing to swap out
> so much that hot pages are getting swapped, or that you simply have a
> working set that's larger than physical memory.

I suppose 'swapin' is the 'Swap - si' column of the 'vmstat' utility, for 
example. OK then if I want to create a script that tell me when memory is 
needed I should monitor this value, right ? (sorry again, my questions are a 
little bit 'corporate'... :-\ )

For my RedHat kernel I'll work on compiling my own... Unfortunately the 
'.spec' of vanilia kernel distributions don't create -BOOT , -smp, etc... 
kernels, which are needed for kickstart installs.

-- 
Mickael Bailly