Re: [patch 12/23] SLUB: Trigger defragmentation from memory reclaim

Christoph Lameter
2007-11-07T18:34:54Z

On Wed, 7 Nov 2007, Johannes Weiner wrote:

> > @@ -210,6 +218,8 @@ unsigned long shrink_slab(unsigned long
> > shrinker->nr += total_scan;
> > }
> > up_read(&shrinker_rwsem);
> > + if (gfp_mask & __GFP_FS)
> > + kmem_cache_defrag(zone ? zone_to_nid(zone) : -1);
> > return ret;
> > }
>
> What about the objects that kmem_cache_defrag() releases? Shouldn't
> they be counted too?
>
> ret += kmem_cache_defrag(...)
>
> Or am I overseeing something here?

kmem_cache_defrag returns the number of pages that were released by defrag
actions.

shrink_slab returns the number of objects released by the shrinkers.
kmem_cache_defrag has no way of knowing how many objects where released by
the kick methods. The kick method may have chosen to reallocate the
object.