Re: Where's all my memory going?

From: Bruce Guenter (bruceg@em.ca)
Date: Thu Jan 10 2002 - 03:45:20 EST

On Wed, Jan 09, 2002 at 08:36:13PM -0200, Rik van Riel wrote:
> Matt's system seems to go from 900 MB free to about
> 300 MB (free + cache).
>
> I doubt qmail would eat 600 MB of RAM (it might, I
> just doubt it) so I'm curious where the RAM is going.

I am seeing the same symptoms, with similar use -- ext3 filesystems
running qmail. Adding up the RSS of all the processes in use gives
about 75MB, while free shows:

             total used free shared buffers cached
Mem: 901068 894088 6980 0 157568 113856
-/+ buffers/cache: 622664 278404
Swap: 1028152 10468 1017684

This are fairly consistent numbers. buffers hovers around 150MB and
cached around 110MB all day. The server is heavy on write traffic.

> Matt, do you see any suspiciously high numbers in
> /proc/slabinfo ?

What would be suspiciously high? The four biggest numbers I see are:

inode_cache 139772 204760 480 25589 25595 1
dentry_cache 184024 326550 128 10885 10885 1
buffer_head 166620 220480 96 4487 5512 1
size-64 102388 174876 64 2964 2964 1

I can post complete details for any who wish to investigate further. I
am not seeing a huge slowdown, but I have no real baseline to compare
against. 

-- 
Bruce Guenter <bruceg@em.ca> http://em.ca/~bruceg/ http://untroubled.org/
OpenPGP key: 699980E8 / D0B7 C8DD 365D A395 29DA  2E2A E96F B2DC 6999 80E8
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