On 4/22/20 10:46 PM, Roman Gushchin wrote: > Switch to per-object accounting of non-root slab objects. > > Charging is performed using obj_cgroup API in the pre_alloc hook. > Obj_cgroup is charged with the size of the object and the size > of metadata: as now it's the size of an obj_cgroup pointer. > If the amount of memory has been charged successfully, the actual > allocation code is executed. Otherwise, -ENOMEM is returned. > > In the post_alloc hook if the actual allocation succeeded, > corresponding vmstats are bumped and the obj_cgroup pointer is saved. > Otherwise, the charge is canceled. > > On the free path obj_cgroup pointer is obtained and used to uncharge > the size of the releasing object. > > Memcg and lruvec counters are now representing only memory used > by active slab objects and do not include the free space. The free > space is shared and doesn't belong to any specific cgroup. > > Global per-node slab vmstats are still modified from (un)charge_slab_page() > functions. The idea is to keep all slab pages accounted as slab pages > on system level. > > Signed-off-by: Roman Gushchin <[email protected]>
Reviewed-by: Vlastimil Babka <[email protected]> Suggestion below: > @@ -568,32 +548,33 @@ static __always_inline int charge_slab_page(struct page > *page, > gfp_t gfp, int order, > struct kmem_cache *s) > { > - int ret; > - > - if (is_root_cache(s)) { > - mod_node_page_state(page_pgdat(page), cache_vmstat_idx(s), > - PAGE_SIZE << order); > - return 0; > - } > +#ifdef CONFIG_MEMCG_KMEM > + if (!is_root_cache(s)) { This could also benefit from memcg_kmem_enabled() static key test AFAICS. Maybe even have a wrapper for both tests together? > + int ret; > > - ret = memcg_alloc_page_obj_cgroups(page, gfp, objs_per_slab(s)); > - if (ret) > - return ret; > + ret = memcg_alloc_page_obj_cgroups(page, gfp, objs_per_slab(s)); You created memcg_alloc_page_obj_cgroups() empty variant for !CONFIG_MEMCG_KMEM but now the only caller is under CONFIG_MEMCG_KMEM. > + if (ret) > + return ret; > > - return memcg_charge_slab(page, gfp, order, s); > + percpu_ref_get_many(&s->memcg_params.refcnt, 1 << order); Perhaps moving this refcount into memcg_alloc_page_obj_cgroups() (maybe the name should be different then) will allow you to not add #ifdef CONFIG_MEMCG_KMEM in this function. Maybe this is all moot after patch 12/19, will find out :) > + } > +#endif > + mod_node_page_state(page_pgdat(page), cache_vmstat_idx(s), > + PAGE_SIZE << order); > + return 0; > } > > static __always_inline void uncharge_slab_page(struct page *page, int order, > struct kmem_cache *s) > { > - if (is_root_cache(s)) { > - mod_node_page_state(page_pgdat(page), cache_vmstat_idx(s), > - -(PAGE_SIZE << order)); > - return; > +#ifdef CONFIG_MEMCG_KMEM > + if (!is_root_cache(s)) { Everything from above also applies here. > + memcg_free_page_obj_cgroups(page); > + percpu_ref_put_many(&s->memcg_params.refcnt, 1 << order); > } > - > - memcg_free_page_obj_cgroups(page); > - memcg_uncharge_slab(page, order, s); > +#endif > + mod_node_page_state(page_pgdat(page), cache_vmstat_idx(s), > + -(PAGE_SIZE << order)); > } > > static inline struct kmem_cache *cache_from_obj(struct kmem_cache *s, void > *x)
