From da77ae2b27ec73a644624a6d4bffc206e2df6bb8 Mon Sep 17 00:00:00 2001 From: Hou Tao Date: Tue, 13 Jun 2023 16:09:19 +0800 Subject: [PATCH] selftests/bpf: Ensure that next_cpu() returns a valid CPU number When using option -a without --prod-affinity or --cons-affinity, if the number of producers and consumers is greater than the number of online CPUs, the benchmark will fail to run as shown below: $ getconf _NPROCESSORS_ONLN 8 $ ./bench bpf-loop -a -p9 Setting up benchmark 'bpf-loop'... setting affinity to CPU #8 failed: -22 Fix it by returning the remainder of next_cpu divided by the number of online CPUs in next_cpu(). Signed-off-by: Hou Tao Link: https://lore.kernel.org/r/20230613080921.1623219-4-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov --- tools/testing/selftests/bpf/bench.c | 3 ++- tools/testing/selftests/bpf/bench.h | 1 + 2 files changed, 3 insertions(+), 1 deletion(-) diff --git a/tools/testing/selftests/bpf/bench.c b/tools/testing/selftests/bpf/bench.c index 0b5d2b5303c99..56f1c166a57b6 100644 --- a/tools/testing/selftests/bpf/bench.c +++ b/tools/testing/selftests/bpf/bench.c @@ -469,7 +469,7 @@ static int next_cpu(struct cpu_set *cpu_set) exit(1); } - return cpu_set->next_cpu++; + return cpu_set->next_cpu++ % env.nr_cpus; } static struct bench_state { @@ -659,6 +659,7 @@ static void collect_measurements(long delta_ns) { int main(int argc, char **argv) { + env.nr_cpus = get_nprocs(); parse_cmdline_args_init(argc, argv); if (env.list) { diff --git a/tools/testing/selftests/bpf/bench.h b/tools/testing/selftests/bpf/bench.h index 402729c6a3ac5..7ff32be3d7300 100644 --- a/tools/testing/selftests/bpf/bench.h +++ b/tools/testing/selftests/bpf/bench.h @@ -27,6 +27,7 @@ struct env { bool quiet; int consumer_cnt; int producer_cnt; + int nr_cpus; struct cpu_set prod_cpus; struct cpu_set cons_cpus; }; -- 2.30.2