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. > 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. > > If we can fix all that up then I wonder whether this particular patch > needs to exist at all. If the kmem_cache is no longer used then we > can simply leave it floating around in memory and the regular cache > shrinking code out of shrink_slab() will clean up any remaining pages. > The kmem_cache itself can be reclaimed via another shrinker, if > necessary? The kmem_cache can only be released if all its objects (used and unused) are released. kmem_cache_shrink drops the unused objects on some internal slab specific list. That may enable us to release the kmem_cache structure. -- 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>