[PATCH bpf-next 0/2] selftests and sample for bpf_proactive_reclaim

[Hui Zhu <hui.zhu@linux.dev>]

From: Hui Zhu <zhuhui@kylinos.cn>

This series follows the bpf_proactive_reclaim() kfunc patch (v14, acked
by Shakeel Butt, reviewed by JP Kobryn and Barry Song). Review feedback
on that series was that ~1200 lines of selftest for a ~20 line kfunc is
overkill, so the test material is split in two:

1/2 is the minimal selftest. It mirrors the memory.reclaim selftest:
charge a cgroup, call the kfunc once, and check the single bounded pass
semantics (one call reclaims at most MEMCG_CHARGE_BATCH pages and, unlike
a write to memory.reclaim, does not retry until the goal is reached).

2/2 moves the complex asynchronous scenario out of the selftests and into
samples/bpf, where it belongs: a BPF program watches the workingset
refaults of a pressured cgroup and, when they grow, reclaims a target
cgroup from a bpf_wq callback through bpf_proactive_reclaim(). It runs
in two modes: bench recreates the high/low priority benchmark of the old
selftest, and watch keeps reclaiming for user-specified cgroups as a
simple proactive-reclaim daemon. Besides exercising the kfunc end to
end, the sample is meant as a design reference for anyone building their
own BPF-driven reclaim policy on bpf_proactive_reclaim(), bpf_wq and the
memcg kfuncs.

Hui Zhu (2):
  selftests/bpf: Add bpf_proactive_reclaim test
  samples/bpf: Add memcg async reclaim example

 samples/bpf/.gitignore                        |    1 +
 samples/bpf/Makefile                          |   10 +-
 samples/bpf/memcg_async_reclaim.bpf.c         |  349 +++++
 samples/bpf/memcg_async_reclaim.h             |   39 +
 samples/bpf/memcg_async_reclaim_user.c        | 1141 +++++++++++++++++
 tools/testing/selftests/bpf/config            |    1 +
 .../bpf/prog_tests/memcg_proactive_reclaim.c  |  124 ++
 .../bpf/progs/memcg_proactive_reclaim.c       |   34 +
 8 files changed, 1698 insertions(+), 1 deletion(-)
 create mode 100644 samples/bpf/memcg_async_reclaim.bpf.c
 create mode 100644 samples/bpf/memcg_async_reclaim.h
 create mode 100644 samples/bpf/memcg_async_reclaim_user.c
 create mode 100644 tools/testing/selftests/bpf/prog_tests/memcg_proactive_reclaim.c
 create mode 100644 tools/testing/selftests/bpf/progs/memcg_proactive_reclaim.c

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2.43.0