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bpf: Don't prefill for unused bpf_mem_cache

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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: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20230908133923.2675053-3-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Hou Tao 2023-09-08 21:39:21 +08:00 committed by Alexei Starovoitov
parent d52b59315b
commit b1d53958b6
1 changed files with 14 additions and 2 deletions
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16
kernel/bpf/memalloc.c
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@ -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);
}
}