δΊ 2015/10/15 5:28, Alexei Starovoitov ει: > On 10/14/15 5:37 AM, Kaixu Xia wrote: >> + event->p_sample_disable = &enabler_event->sample_disable; > > I don't like it as a concept and it's buggy implementation. > What happens here when enabler is alive, but other event is destroyed? > >> --- a/kernel/trace/bpf_trace.c >> +++ b/kernel/trace/bpf_trace.c >> @@ -221,9 +221,12 @@ static u64 bpf_perf_event_sample_control(u64 r1, u64 >> index, u64 flag, u64 r4, u6 >> struct bpf_array *array = container_of(map, struct bpf_array, map); >> struct perf_event *event; >> >> - if (unlikely(index >= array->map.max_entries)) >> + if (unlikely(index > array->map.max_entries)) >> return -E2BIG; >> >> + if (index == array->map.max_entries) >> + index = 0; > > what is this hack for ? > > Either use notification and user space disable or > call bpf_perf_event_sample_control() manually for each cpu.
I will discard current implemention that controlling a set of perf events by the 'enabler' event. Call bpf_perf_event_sample_control() manually for each cpu is fine. Maybe we can add a loop to control all the events stored in maps by judging the index, OK? > > > > . > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
