On Thu, 8 Nov 2012 23:31:16 +0100 Glauber Costa <glommer@xxxxxxxxxxxxx> wrote: > On 11/08/2012 08:21 PM, Andrew Morton wrote: > > On Thu, 8 Nov 2012 17:15:36 +0000 > > Christoph Lameter <cl@xxxxxxxxx> wrote: > > > >> On Wed, 7 Nov 2012, Andrew Morton wrote: > >> > >>> What's up with kmem_cache_shrink? It's global and exported to modules > >>> but its only external caller is some weird and hopelessly poorly > >>> documented site down in drivers/acpi/osl.c. slab and slob implement > >>> kmem_cache_shrink() *only* for acpi! wtf? Let's work out what acpi is > >>> trying to actually do there, then do it properly, then killkillkill! > >> > >> 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. > > > >>> Secondly, as slab and slub (at least) have the ability to shed cached > >>> memory, why aren't they hooked into the core cache-shinking machinery. > >>> After all, it's called "shrink_slab"! > >> > >> 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. > > > > AFACIT, this is correct and desirable behaviour for shrinking > > slab's internal caches. > > > > I believe calling this from shrink_slab() is not a bad idea at all. If > you're all in favour, I'll cook a patch for this soon It sounds like a pretty big change but yes, well worth exploring. I'd still like to give ACPI a thwap. That kmem_cache_shrink() in drivers/acpi/osl.c was added unchangelogged in a megapatch (73459f73e5d1602c59) so it's a mystery. Cc's optimistically added. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>