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selftests/bpf: Fix arena_spin_lock on systems with less than 16 CPUs

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test_arena_spin_lock_size() explicitly requires having at least 2 CPUs,
but if the machine has less than 16, then pthread_setaffinity_np() call
in spin_lock_thread() fails.

Cap threads to the number of CPUs.

Alternative solutions are raising the number of required CPUs to 16, or
pinning multiple threads to the same CPU, but they are not that useful.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Link: https://lore.kernel.org/r/20250424165525.154403-3-iii@linux.ibm.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Ilya Leoshkevich 2025-04-24 18:41:26 +02:00 committed by Alexei Starovoitov
parent ddfd1f30b5
commit 0240e5a943
1 changed files with 8 additions and 6 deletions
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14
tools/testing/selftests/bpf/prog_tests/arena_spin_lock.c
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@ -51,9 +51,11 @@ static void test_arena_spin_lock_size(int size)
struct arena_spin_lock *skel;
pthread_t thread_id[16];
int prog_fd, i, err;
int nthreads;
void *ret;
if (get_nprocs() < 2) {
nthreads = MIN(get_nprocs(), ARRAY_SIZE(thread_id));
if (nthreads < 2) {
test__skip();
return;
}
@ -66,25 +68,25 @@ static void test_arena_spin_lock_size(int size)
goto end;
}
skel->bss->cs_count = size;
skel->bss->limit = repeat * 16;
skel->bss->limit = repeat * nthreads;
ASSERT_OK(pthread_barrier_init(&barrier, NULL, 16), "barrier init");
ASSERT_OK(pthread_barrier_init(&barrier, NULL, nthreads), "barrier init");
prog_fd = bpf_program__fd(skel->progs.prog);
for (i = 0; i < 16; i++) {
for (i = 0; i < nthreads; i++) {
err = pthread_create(&thread_id[i], NULL, &spin_lock_thread, &prog_fd);
if (!ASSERT_OK(err, "pthread_create"))
goto end_barrier;
}
for (i = 0; i < 16; i++) {
for (i = 0; i < nthreads; i++) {
if (!ASSERT_OK(pthread_join(thread_id[i], &ret), "pthread_join"))
goto end_barrier;
if (!ASSERT_EQ(ret, &prog_fd, "ret == prog_fd"))
goto end_barrier;
}
ASSERT_EQ(skel->bss->counter, repeat * 16, "check counter value");
ASSERT_EQ(skel->bss->counter, repeat * nthreads, "check counter value");
end_barrier:
pthread_barrier_destroy(&barrier);