Re: [PATCH bpf-next] selftests/bpf: simplify the kernel_count bench trigger

On Mon, Nov 10, 2025 at 5:49 AM Menglong Dong menglong8.dong@gmail.com wrote:

Remove the "trigger_count" in trigger_bench.c and reuse trigger_driver() instead for trigger_kernel_count_setup().

With the calling to bpf_get_numa_node_id(), the result for "kernel_count" will become a little more accurate.

"more accurate" is a bit misleading here. I think you meant that it will do same amount of helper calls as fentry and other benchmarks, and in that sense will be closer as a baseline comparison, is that right? Can you clarify that in the next revision, please?

It will also easier if we want to test the performance of livepatch, just hook the bpf_get_numa_node_id() and run the "kernel_count" bench trigger.

Signed-off-by: Menglong Dong dongml2@chinatelecom.cn

.../selftests/bpf/benchs/bench_trigger.c | 5 +---- .../testing/selftests/bpf/progs/trigger_bench.c | 17 +++++------------ 2 files changed, 6 insertions(+), 16 deletions(-)

diff --git a/tools/testing/selftests/bpf/benchs/bench_trigger.c b/tools/testing/selftests/bpf/benchs/bench_trigger.c index 1e2aff007c2a..34fd8fa3b803 100644 --- a/tools/testing/selftests/bpf/benchs/bench_trigger.c +++ b/tools/testing/selftests/bpf/benchs/bench_trigger.c @@ -179,11 +179,8 @@ static void trigger_syscall_count_setup(void) static void trigger_kernel_count_setup(void) { setup_ctx();

•   bpf_program__set_autoload(ctx.skel->progs.trigger_driver, false);
  

•   bpf_program__set_autoload(ctx.skel->progs.trigger_count, true);
  

•   ctx.skel->rodata->kernel_count = 1;
    load_ctx();
  

•   /* override driver program */
  

•   ctx.driver_prog_fd = bpf_program__fd(ctx.skel->progs.trigger_count);
  

}

static void trigger_kprobe_setup(void) diff --git a/tools/testing/selftests/bpf/progs/trigger_bench.c b/tools/testing/selftests/bpf/progs/trigger_bench.c index 3d5f30c29ae3..6564d1909c7b 100644 --- a/tools/testing/selftests/bpf/progs/trigger_bench.c +++ b/tools/testing/selftests/bpf/progs/trigger_bench.c @@ -39,26 +39,19 @@ int bench_trigger_uprobe_multi(void *ctx) return 0; }

+const volatile int kernel_count = 0;

nit: use bool? it's not a counter, no need to use int here

const volatile int batch_iters = 0;

-SEC("?raw_tp") -int trigger_count(void *ctx) -{

•   int i;
  

•   for (i = 0; i < batch_iters; i++)
  

•           inc_counter();
  

•   return 0;
  

-}

SEC("?raw_tp") int trigger_driver(void *ctx) { int i;

•   for (i = 0; i < batch_iters; i++)
  

•   for (i = 0; i < batch_iters; i++) {
            (void)bpf_get_numa_node_id(); /* attach point for benchmarking */
  

•           if (kernel_count)
  

•                   inc_counter();
  

•   }
  

tbh, I wouldn't touch trigger_driver() adding unnecessary if conditions to it. It's fine, IMO, to have bpf_get_numa_node_id() call in trigger_count() for being closer in terms of actual work being done, but I'd keep trigger_driver and trigger_count separate (maybe renaming trigger_count to trigger_kernel_count would help, I don't know)

pw-bot: cr

    return 0;

}

2.51.2