Re: [RFC PATCH bpf-next] libbpf: remove sample_period init in perf_buffer

Jiri Olsa
2025-04-22T13:43:47Z

On Tue, Apr 22, 2025 at 05:15:58PM +0800, Tao Chen wrote:
> It seems that sample_period no used in perf buffer, actually only
> wakeup_events valid about events aggregation for wakeup. So remove
> it to avoid causing confusion.

I don't see too much confusion in keeping it, but I think it
should be safe to remove it

PERF_COUNT_SW_BPF_OUTPUT is "trigered" by bpf_perf_event_output,
AFAICS there's no path checking on sample_period for this event
used in context of perf_buffer__new, Namhyung, thoughts?

thanks,
jirka

>
> Fixes: fb84b8224655 ("libbpf: add perf buffer API")
> Signed-off-by: Tao Chen <chen.dylane@linux.dev>
> ---
> tools/lib/bpf/libbpf.c | 1 -
> 1 file changed, 1 deletion(-)
>
> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index 194809da5172..1830e3c011a5 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -13306,7 +13306,6 @@ struct perf_buffer *perf_buffer__new(int map_fd, size_t page_cnt,
> attr.config = PERF_COUNT_SW_BPF_OUTPUT;
> attr.type = PERF_TYPE_SOFTWARE;
> attr.sample_type = PERF_SAMPLE_RAW;
> - attr.sample_period = sample_period;
> attr.wakeup_events = sample_period;
>
> p.attr = &attr;
> --
> 2.43.0
>