Re: [PATCH v6 25/29] memcg/sl[au]b: shrink dead caches

Christoph Lameter
2012-11-09T20:04:33Z

On Thu, 8 Nov 2012, Andrew Morton wrote:

> > kmem_cache_shrink is also used internally. Its simply releasing unused
> > cached objects.
>
> Only in slub. It could be removed outright from the others and
> simplified in slub.

Both SLAB and SLUB must purge their queues before closing/destroying a
cache. There is not much code that can be eliminated.

> > Because the core cache shrinking needs the slab caches to free up memory
> > from inodes and dentries. We could call kmem_cache_shrink at the end of
> > the shrink passes in vmscan. The price would be that the caches would have
> > to be repopulated when new allocations occur.
>
> Well, the shrinker shouldn't strips away all the cache. It will perform
> a partial trim, the magnitude of which increases with perceived
> external memory pressure.

The partial trim of the objects cached by SLAB is performed in 2 second
intervals from the cache reaper.

We are talking here about flushing all
the cached objects from the inode and dentry cache etc in vmscan right?