Commit da77ae2b authored by Hou Tao's avatar Hou Tao Committed by Alexei Starovoitov
Browse files

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: default avatarHou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20230613080921.1623219-4-houtao@huaweicloud.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent ea400d13

tools/testing/selftests/bpf/bench.c

+2 −1
Original line number Diff line number Diff line
@@ -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) {

tools/testing/selftests/bpf/bench.h

+1 −0
Original line number Diff line number Diff line
@@ -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;

};