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* [PATCH bpf-next v5 0/8] bpf: Reduce memory usage for bpf_global_percpu_ma
@ 2023-12-21  4:59 Yonghong Song
  2023-12-21  5:00 ` [PATCH bpf-next v5 1/8] bpf: Avoid unnecessary extra percpu memory allocation Yonghong Song
                   ` (7 more replies)
  0 siblings, 8 replies; 14+ messages in thread
From: Yonghong Song @ 2023-12-21  4:59 UTC (permalink / raw)
  To: bpf
  Cc: Alexei Starovoitov, Andrii Nakryiko, Daniel Borkmann, kernel-team,
	Martin KaFai Lau

Currently when a bpf program intends to allocate memory for percpu kptr,
the verifier will call bpf_mem_alloc_init() to prefill all supported
unit sizes and this caused memory consumption very big for large number
of cpus. For example, for 128-cpu system, the total memory consumption
with initial prefill is ~175MB. Things will become worse for systems
with even more cpus.

Patch 1 avoids unnecessary extra percpu memory allocation.
Patch 2 adds objcg to bpf_mem_alloc at init stage so objcg can be
associated with root cgroup and objcg can be passed to later
bpf_mem_alloc_percpu_unit_init().
Patch 3 addresses memory consumption issue by avoiding to prefill
with all unit sizes, i.e. only prefilling with user specified size.
Patch 4 further reduces memory consumption by limiting the
number of prefill entries for percpu memory allocation.
Patch 5 has much smaller low/high watermarks for percpu allocation
to reduce memory consumption.
Patch 6 rejects percpu memory allocation with bpf_global_percpu_ma
when allocation size is greater than 512 bytes.
Patch 7 fixed test_bpf_ma test due to Patch 5.
Patch 8 added one test to show the verification failure log message.

Changelogs:
  v4 -> v5:
    . Do not do bpf_global_percpu_ma initialization at init stage, instead
      doing initialization when the verifier knows it is going to be used
      by bpf prog.
    . Using much smaller low/high watermarks for percpu allocation.
  v3 -> v4:
    . Add objcg to bpf_mem_alloc during init stage.
    . Initialize objcg at init stage but use it in bpf_mem_alloc_percpu_unit_init().
    . Remove check_obj_size() in bpf_mem_alloc_percpu_unit_init().
  v2 -> v3:
    . Clear the bpf_mem_cache if prefill fails.
    . Change test_bpf_ma percpu allocation tests to use bucket_size
      as allocation size instead of bucket_size - 8.
    . Remove __GFP_ZERO flag from __alloc_percpu_gfp() call.
  v1 -> v2:
    . Avoid unnecessary extra percpu memory allocation.
    . Add a separate function to do bpf_global_percpu_ma initialization
    . promote.
    . Promote function static 'sizes' array to file static.
    . Add comments to explain to refill only one item for percpu alloc.

Yonghong Song (8):
  bpf: Avoid unnecessary extra percpu memory allocation
  bpf: Add objcg to bpf_mem_alloc
  bpf: Allow per unit prefill for non-fix-size percpu memory allocator
  bpf: Refill only one percpu element in memalloc
  bpf: Use smaller low/high marks for percpu allocation
  bpf: Limit up to 512 bytes for bpf_global_percpu_ma allocation
  selftests/bpf: Cope with 512 bytes limit with bpf_global_percpu_ma
  selftests/bpf: Add a selftest with > 512-byte percpu allocation size

 include/linux/bpf_mem_alloc.h                 |  8 ++
 kernel/bpf/memalloc.c                         | 98 ++++++++++++++++---
 kernel/bpf/verifier.c                         | 42 +++++---
 .../selftests/bpf/prog_tests/test_bpf_ma.c    | 20 ++--
 .../selftests/bpf/progs/percpu_alloc_fail.c   | 18 ++++
 .../testing/selftests/bpf/progs/test_bpf_ma.c | 66 ++++++-------
 6 files changed, 186 insertions(+), 66 deletions(-)

-- 
2.34.1


^ permalink raw reply	[flat|nested] 14+ messages in thread
end of thread, other threads:[~2023-12-21 16:53 UTC | newest]

Thread overview: 14+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2023-12-21  4:59 [PATCH bpf-next v5 0/8] bpf: Reduce memory usage for bpf_global_percpu_ma Yonghong Song
2023-12-21  5:00 ` [PATCH bpf-next v5 1/8] bpf: Avoid unnecessary extra percpu memory allocation Yonghong Song
2023-12-21  5:00 ` [PATCH bpf-next v5 2/8] bpf: Add objcg to bpf_mem_alloc Yonghong Song
2023-12-21  5:00 ` [PATCH bpf-next v5 3/8] bpf: Allow per unit prefill for non-fix-size percpu memory allocator Yonghong Song
2023-12-21  6:26   ` Hou Tao
2023-12-21  7:16     ` Yonghong Song
2023-12-21  7:52       ` Yonghong Song
2023-12-21  8:42         ` Hou Tao
2023-12-21 16:53           ` Yonghong Song
2023-12-21  5:00 ` [PATCH bpf-next v5 4/8] bpf: Refill only one percpu element in memalloc Yonghong Song
2023-12-21  5:00 ` [PATCH bpf-next v5 5/8] bpf: Use smaller low/high marks for percpu allocation Yonghong Song
2023-12-21  5:00 ` [PATCH bpf-next v5 6/8] bpf: Limit up to 512 bytes for bpf_global_percpu_ma allocation Yonghong Song
2023-12-21  5:00 ` [PATCH bpf-next v5 7/8] selftests/bpf: Cope with 512 bytes limit with bpf_global_percpu_ma Yonghong Song
2023-12-21  5:00 ` [PATCH bpf-next v5 8/8] selftests/bpf: Add a selftest with > 512-byte percpu allocation size Yonghong Song

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