On Wed, Jun 17, 2020 at 04:35:28PM -0700, Andrew Morton wrote: > On Mon, 8 Jun 2020 16:06:52 -0700 Roman Gushchin <guro@xxxxxx> wrote: > > > Instead of having two sets of kmem_caches: one for system-wide and > > non-accounted allocations and the second one shared by all accounted > > allocations, we can use just one. > > > > The idea is simple: space for obj_cgroup metadata can be allocated > > on demand and filled only for accounted allocations. > > > > It allows to remove a bunch of code which is required to handle > > kmem_cache clones for accounted allocations. There is no more need > > to create them, accumulate statistics, propagate attributes, etc. > > It's a quite significant simplification. > > > > Also, because the total number of slab_caches is reduced almost twice > > (not all kmem_caches have a memcg clone), some additional memory > > savings are expected. On my devvm it additionally saves about 3.5% > > of slab memory. > > > > This ran afoul of Vlastimil's "mm, slab/slub: move and improve > cache_from_obj()" > (http://lkml.kernel.org/r/20200610163135.17364-10-vbabka@xxxxxxx). I > resolved things as below. Not too sure about slab.c's > cache_from_obj()... It can actually be as simple as: static inline struct kmem_cache *cache_from_obj(struct kmem_cache *s, void *x) { return s; } But I wonder if we need it at all, or maybe we wanna rename it to something like obj_check_kmem_cache(void *obj, struct kmem_cache *s), because it has now only debug purposes. Let me and Vlastimil figure it out and send a follow-up patch. Your version is definitely correct. Thanks!
