selftests/bpf: Avoid spurious failures perf_link

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perf_link creates a system-wide perf event pinned to CPU 0 (pid=-1, cpu=0)
and also pins the test thread to CPU 0. Under concurrent selftests this
can lead to cross-test interference and CPU 0 contention, making the test
flaky.

Create a per-task perf event instead (pid=0, cpu=-1) and drop CPU pinning
from burn_cpu(). Use barrier() to prevent the burn loop from being
optimized away. Drop the serial_ prefix so the test can run in parallel.
Also remove the stale TODO comment.

Tested:
  ./test_progs -t perf_link -vv
  ./test_progs -j$(nproc) -t perf_link -vv
  for i in $(seq 1 50); do ./test_progs -j$(nproc) -t perf_link; done

Signed-off-by: Sun Jian <sun.jian.kdev@gmail.com>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20260305084306.283983-1-sun.jian.kdev@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

...

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Sun Jian 2026-03-05 16:43:05 +08:00 • committed by Alexei Starovoitov

parent 77378dabb5

commit 888329ba6c

1 changed files with 5 additions and 15 deletions

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tools/testing/selftests/bpf/prog_tests/perf_link.c

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