From b77d5b1b83e3e14870224de7c63f115a2dc44e9a Mon Sep 17 00:00:00 2001 From: Muchun Song Date: Fri, 29 Apr 2022 20:30:44 +0800 Subject: mm: slab: optimize memcg_slab_free_hook() Most callers of memcg_slab_free_hook() already know the slab, which could be passed to memcg_slab_free_hook() directly to reduce the overhead of an another call of virt_to_slab(). For bulk freeing of objects, the call of slab_objcgs() in the loop in memcg_slab_free_hook() is redundant as well. Rework memcg_slab_free_hook() and build_detached_freelist() to reduce those unnecessary overhead and make memcg_slab_free_hook() can handle bulk freeing in slab_free(). Move the calling site of memcg_slab_free_hook() from do_slab_free() to slab_free() for slub to make the code clearer since the logic is weird (e.g. the caller need to judge whether it needs to call memcg_slab_free_hook()). It is easy to make mistakes like missing calling of memcg_slab_free_hook() like fixes of: commit d1b2cf6cb84a ("mm: memcg/slab: uncharge during kmem_cache_free_bulk()") commit ae085d7f9365 ("mm: kfence: fix missing objcg housekeeping for SLAB") This optimization is mainly for bulk objects freeing. The following numbers is shown for 16-object freeing. before after kmem_cache_free_bulk: ~430 ns ~400 ns The overhead is reduced by about 7% for 16-object freeing. Signed-off-by: Muchun Song Reviewed-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> Link: https://lore.kernel.org/r/20220429123044.37885-1-songmuchun@bytedance.com Signed-off-by: Vlastimil Babka --- mm/slab.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'mm/slab.c') diff --git a/mm/slab.c b/mm/slab.c index f7d6ca702018..764cbadba69c 100644 --- a/mm/slab.c +++ b/mm/slab.c @@ -3406,9 +3406,10 @@ static __always_inline void __cache_free(struct kmem_cache *cachep, void *objp, { bool init; + memcg_slab_free_hook(cachep, virt_to_slab(objp), &objp, 1); + if (is_kfence_address(objp)) { kmemleak_free_recursive(objp, cachep->flags); - memcg_slab_free_hook(cachep, &objp, 1); __kfence_free(objp); return; } @@ -3441,7 +3442,6 @@ void ___cache_free(struct kmem_cache *cachep, void *objp, check_irq_off(); kmemleak_free_recursive(objp, cachep->flags); objp = cache_free_debugcheck(cachep, objp, caller); - memcg_slab_free_hook(cachep, &objp, 1); /* * Skip calling cache_free_alien() when the platform is not numa. -- cgit