Re: dentry_cache using up all my zone normal memory -- also seen on 2.6.14-rc2

["Christopher Friesen" <cfriesen@nortel.com>]

Sonny Rao wrote:

> If I'm reading this correctly, you seem to have about 1.2 million
> files open and about 3.9 million dentrys objects in lowmem with almost
> no fragmentation..  for those files which are open there certainly
> will be a dentry attached to the inode (how big is inode cache?), but
> the shrinker should be trying to reclaim memory from the other 2.7
> million objects I would think.

I don't know what the code is actually doing.  This is testcase 
"rename14" from the LTP suite.  It runs fine on ppc, ppc64, dual-xeon, 
and Xscale.

The inode cache is small...under 300 objects.

> Based on the lack of fragmentation I would guess that either the shrinker isn't
> running or those dentrys are otherwise pinned somehow (parent
> directorys of the open files?)  What does the directory structure look
> like?

No idea.

> Just for kicks (again), have you tried ratcheting up the
> /proc/sys/vm/vfs_cache_pressure tunable by a few orders of magnitude ?

Nope.  I'm currently rebooting with an instrumentation patch for dentry, 
may try this too.

Chris