From 9028cdeb38e1f37d63cb3154799dd259b67e879e Mon Sep 17 00:00:00 2001 From: Shakeel Butt Date: Thu, 5 Sep 2024 10:34:22 -0700 Subject: memcg: add charging of already allocated slab objects At the moment, the slab objects are charged to the memcg at the allocation time. However there are cases where slab objects are allocated at the time where the right target memcg to charge it to is not known. One such case is the network sockets for the incoming connection which are allocated in the softirq context. Couple hundred thousand connections are very normal on large loaded server and almost all of those sockets underlying those connections get allocated in the softirq context and thus not charged to any memcg. However later at the accept() time we know the right target memcg to charge. Let's add new API to charge already allocated objects, so we can have better accounting of the memory usage. To measure the performance impact of this change, tcp_crr is used from the neper [1] performance suite. Basically it is a network ping pong test with new connection for each ping pong. The server and the client are run inside 3 level of cgroup hierarchy using the following commands: Server: $ tcp_crr -6 Client: $ tcp_crr -6 -c -H ${server_ip} If the client and server run on different machines with 50 GBPS NIC, there is no visible impact of the change. For the same machine experiment with v6.11-rc5 as base. base (throughput) with-patch tcp_crr 14545 (+- 80) 14463 (+- 56) It seems like the performance impact is within the noise. Link: https://github.com/google/neper [1] Signed-off-by: Shakeel Butt Reviewed-by: Roman Gushchin Reviewed-by: Yosry Ahmed Acked-by: Paolo Abeni # net Signed-off-by: Vlastimil Babka --- mm/slub.c | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 53 insertions(+) (limited to 'mm/slub.c') diff --git a/mm/slub.c b/mm/slub.c index 95977f25a760..aa512de974e7 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2185,6 +2185,45 @@ void memcg_slab_free_hook(struct kmem_cache *s, struct slab *slab, void **p, __memcg_slab_free_hook(s, slab, p, objects, obj_exts); } + +static __fastpath_inline +bool memcg_slab_post_charge(void *p, gfp_t flags) +{ + struct slabobj_ext *slab_exts; + struct kmem_cache *s; + struct folio *folio; + struct slab *slab; + unsigned long off; + + folio = virt_to_folio(p); + if (!folio_test_slab(folio)) { + return folio_memcg_kmem(folio) || + (__memcg_kmem_charge_page(folio_page(folio, 0), flags, + folio_order(folio)) == 0); + } + + slab = folio_slab(folio); + s = slab->slab_cache; + + /* + * Ignore KMALLOC_NORMAL cache to avoid possible circular dependency + * of slab_obj_exts being allocated from the same slab and thus the slab + * becoming effectively unfreeable. + */ + if (is_kmalloc_normal(s)) + return true; + + /* Ignore already charged objects. */ + slab_exts = slab_obj_exts(slab); + if (slab_exts) { + off = obj_to_index(s, slab, p); + if (unlikely(slab_exts[off].objcg)) + return true; + } + + return __memcg_slab_post_alloc_hook(s, NULL, flags, 1, &p); +} + #else /* CONFIG_MEMCG */ static inline bool memcg_slab_post_alloc_hook(struct kmem_cache *s, struct list_lru *lru, @@ -2198,6 +2237,11 @@ static inline void memcg_slab_free_hook(struct kmem_cache *s, struct slab *slab, void **p, int objects) { } + +static inline bool memcg_slab_post_charge(void *p, gfp_t flags) +{ + return true; +} #endif /* CONFIG_MEMCG */ #ifdef CONFIG_SLUB_RCU_DEBUG @@ -4105,6 +4149,15 @@ void *kmem_cache_alloc_lru_noprof(struct kmem_cache *s, struct list_lru *lru, } EXPORT_SYMBOL(kmem_cache_alloc_lru_noprof); +bool kmem_cache_charge(void *objp, gfp_t gfpflags) +{ + if (!memcg_kmem_online()) + return true; + + return memcg_slab_post_charge(objp, gfpflags); +} +EXPORT_SYMBOL(kmem_cache_charge); + /** * kmem_cache_alloc_node - Allocate an object on the specified node * @s: The cache to allocate from. -- cgit v1.2.3-70-g09d2