Commit b1d53958 authored by Hou Tao's avatar Hou Tao Committed by Alexei Starovoitov
Browse files

bpf: Don't prefill for unused bpf_mem_cache 



When the unit_size of a bpf_mem_cache is unmatched with the object_size
of the underlying slab cache, the bpf_mem_cache will not be used, and
the allocation will be redirected to a bpf_mem_cache with a bigger
unit_size instead, so there is no need to prefill for these
unused bpf_mem_caches.

Signed-off-by: default avatarHou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20230908133923.2675053-3-houtao@huaweicloud.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent d52b5931

kernel/bpf/memalloc.c

+14 −2
Original line number Diff line number Diff line
@@ -459,8 +459,7 @@ static void notrace irq_work_raise(struct bpf_mem_cache *c) 
 * Typical case will be between 11K and 116K closer to 11K.

 * bpf progs can and should share bpf_mem_cache when possible.

 */



static void prefill_mem_cache(struct bpf_mem_cache *c, int cpu)

static void init_refill_work(struct bpf_mem_cache *c)

{

	init_irq_work(&c->refill_work, bpf_mem_refill);

	if (c->unit_size <= 256) {
@@ -476,7 +475,10 @@ static void prefill_mem_cache(struct bpf_mem_cache *c, int cpu) 
		c->high_watermark = max(96 * 256 / c->unit_size, 3);

	}

	c->batch = max((c->high_watermark - c->low_watermark) / 4 * 3, 1);

}



static void prefill_mem_cache(struct bpf_mem_cache *c, int cpu)

{

	/* To avoid consuming memory assume that 1st run of bpf

	 * prog won't be doing more than 4 map_update_elem from

	 * irq disabled region
@@ -521,6 +523,7 @@ int bpf_mem_alloc_init(struct bpf_mem_alloc *ma, int size, bool percpu) 
			c->objcg = objcg;

			c->percpu_size = percpu_size;

			c->tgt = c;

			init_refill_work(c);

			prefill_mem_cache(c, cpu);

		}

		ma->cache = pc;
@@ -544,6 +547,15 @@ int bpf_mem_alloc_init(struct bpf_mem_alloc *ma, int size, bool percpu) 
			c->unit_size = sizes[i];

			c->objcg = objcg;

			c->tgt = c;



			init_refill_work(c);

			/* Another bpf_mem_cache will be used when allocating

			 * c->unit_size in bpf_mem_alloc(), so doesn't prefill

			 * for the bpf_mem_cache because these free objects will

			 * never be used.

			 */

			if (i != bpf_mem_cache_idx(c->unit_size))

				continue;

			prefill_mem_cache(c, cpu);

		}

	}