From 7468048237b8a99c03e1325b11373f9b29ef4139 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Wed, 5 Jul 2023 20:34:39 -0700 Subject: [PATCH] bpf: Further refactor alloc_bulk(). In certain scenarios alloc_bulk() might be taking free objects mainly from free_by_rcu_ttrace list. In such case get_memcg() and set_active_memcg() are redundant, but they show up in perf profile. Split the loop and only set memcg when allocating from slab. No performance difference in this patch alone, but it helps in combination with further patches. Signed-off-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann Acked-by: Hou Tao Link: https://lore.kernel.org/bpf/20230706033447.54696-7-alexei.starovoitov@gmail.com --- kernel/bpf/memalloc.c | 30 ++++++++++++++++++------------ 1 file changed, 18 insertions(+), 12 deletions(-) diff --git a/kernel/bpf/memalloc.c b/kernel/bpf/memalloc.c index 052fc80..0ee566a 100644 --- a/kernel/bpf/memalloc.c +++ b/kernel/bpf/memalloc.c @@ -196,8 +196,6 @@ static void alloc_bulk(struct bpf_mem_cache *c, int cnt, int node) void *obj; int i; - memcg = get_memcg(c); - old_memcg = set_active_memcg(memcg); for (i = 0; i < cnt; i++) { /* * free_by_rcu_ttrace is only manipulated by irq work refill_work(). @@ -212,16 +210,24 @@ static void alloc_bulk(struct bpf_mem_cache *c, int cnt, int node) * numa node and it is not a guarantee. */ obj = __llist_del_first(&c->free_by_rcu_ttrace); - if (!obj) { - /* Allocate, but don't deplete atomic reserves that typical - * GFP_ATOMIC would do. irq_work runs on this cpu and kmalloc - * will allocate from the current numa node which is what we - * want here. - */ - obj = __alloc(c, node, GFP_NOWAIT | __GFP_NOWARN | __GFP_ACCOUNT); - if (!obj) - break; - } + if (!obj) + break; + add_obj_to_free_list(c, obj); + } + if (i >= cnt) + return; + + memcg = get_memcg(c); + old_memcg = set_active_memcg(memcg); + for (; i < cnt; i++) { + /* Allocate, but don't deplete atomic reserves that typical + * GFP_ATOMIC would do. irq_work runs on this cpu and kmalloc + * will allocate from the current numa node which is what we + * want here. + */ + obj = __alloc(c, node, GFP_NOWAIT | __GFP_NOWARN | __GFP_ACCOUNT); + if (!obj) + break; add_obj_to_free_list(c, obj); } set_active_memcg(old_memcg); -- 2.7.4