Exponential memory usage?

[Eric Sandeen]

On 3/28/14, 12:53 PM, Tap wrote:
> I have a Linux CentOs-based (6.5) system, running Linux 3.10.29
> beneath xen 4.2.3-26 with a raid array as follows:

<snip>

> Anyway at some point the system had become unusable.  Something as
> simple as:
> 
> find  /raid -type f -- or -- ls -lR /raid
> 
> Would walk the entire system out of RAM.  Looking at slabtop it looks
> like this is due mostly to xfs_inode memory usage.  Note that since
> these problems began I stopped running all sub-ordinate domains and
> am now only running dom0.  In fact I've allocated all 32 GB to that
> domain, and memory problems still persist.

Out of?  Did the OOM-killer actually show up, or did you simply see
memory usage rise?

The dcache is tenacious.  dentries are cached pretty aggressively, and
those in turn will pin the vfs/xfs inodes.

But memory is there to be used; unless you actually see problems,
then the system is likely working as it should be.

<snip>

> Note:  FWIW Un-mounting the filesystem also recovers the memory.

Yep, that would clear out the cache.

-Eric