diff options
| author | Yonghong Song <yonghong.song@linux.dev> | 2023-12-21 19:17:55 -0800 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2024-01-03 21:08:25 -0800 |
| commit | 0e2ba9f96f9b82893ba19170ae48d46003f8ef44 (patch) | |
| tree | 5b253ef511576f6cf1247fad149ecdd81401f5a0 /kernel/bpf | |
| parent | 5b95e638f134e552b5ba2976326c02babe248615 (diff) | |
bpf: Use smaller low/high marks for percpu allocation
Currently, refill low/high marks are set with the assumption
of normal non-percpu memory allocation. For example, for
an allocation size 256, for non-percpu memory allocation,
low mark is 32 and high mark is 96, resulting in the
batch allocation of 48 elements and the allocated memory
will be 48 * 256 = 12KB for this particular cpu.
Assuming an 128-cpu system, the total memory consumption
across all cpus will be 12K * 128 = 1.5MB memory.
This might be okay for non-percpu allocation, but may not be
good for percpu allocation, which will consume 1.5MB * 128 = 192MB
memory in the worst case if every cpu has a chance of memory
allocation.
In practice, percpu allocation is very rare compared to
non-percpu allocation. So let us have smaller low/high marks
which can avoid unnecessary memory consumption.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Acked-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20231222031755.1289671-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'kernel/bpf')
| -rw-r--r-- | kernel/bpf/memalloc.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/kernel/bpf/memalloc.c b/kernel/bpf/memalloc.c index a8ee6fb8401c..460c8f38fed6 100644 --- a/kernel/bpf/memalloc.c +++ b/kernel/bpf/memalloc.c @@ -464,11 +464,17 @@ static void notrace irq_work_raise(struct bpf_mem_cache *c) * consume ~ 11 Kbyte per cpu. * Typical case will be between 11K and 116K closer to 11K. * bpf progs can and should share bpf_mem_cache when possible. + * + * Percpu allocation is typically rare. To avoid potential unnecessary large + * memory consumption, set low_mark = 1 and high_mark = 3, resulting in c->batch = 1. */ static void init_refill_work(struct bpf_mem_cache *c) { init_irq_work(&c->refill_work, bpf_mem_refill); - if (c->unit_size <= 256) { + if (c->percpu_size) { + c->low_watermark = 1; + c->high_watermark = 3; + } else if (c->unit_size <= 256) { c->low_watermark = 32; c->high_watermark = 96; } else { |