Re: inode cache, dentry cache, buffer heads usage

[Dipankar Sarma <dipankar@in.ibm.com>]

On Wed, Mar 09, 2005 at 01:29:23PM -0800, Badari Pulavarty wrote:
> On Wed, 2005-03-09 at 13:27, Dipankar Sarma wrote:
> > On Wed, Mar 09, 2005 at 10:55:58AM -0800, Badari Pulavarty wrote:
> > > Hi,
> > > 
> > > We have a 8-way P-III, 16GB RAM running 2.6.8-1. We use this as
> > > our server to keep source code, cscopes and do the builds.
> > > This machine seems to slow down over the time. One thing we
> > > keep noticing is it keeps running out of lowmem. Most of 
> > > the lowmem is used for ext3 inode cache + dentry cache +
> > > bufferheads + Buffers. So we did 2:2 split - but it improved
> > > thing, but again run into same issues.
> > > 
> > > So, why is these slab cache are not getting purged/shrinked even
> > > under memory pressure ? (I have seen lowmem as low as 6MB). What
> > > can I do to keep the machine healthy ?
> > 
> > How does /proc/sys/fs/dentry-state look when you run low on lowmem ?
> 
> 
> 
> badari@kernel:~$ cat /proc/sys/fs/dentry-state
> 1434093 1348947 45      0       0       0
> badari@kernel:~$ grep dentry /proc/slabinfo
> dentry_cache      1434094 1857519    144   27    1 : tunables  120  
> 60    8 : slabdata  68797  68797      0

Hmm.. so we are not shrinking dcache despite a large number of
unsed dentries. That is where we need to look. Will dig a bit
tomorrow.

Thanks
Dipankar