On Thu, Apr 08, 2021 at 05:28:10PM +0000, Song Liu wrote: > > > > On Apr 8, 2021, at 10:20 AM, Jiri Olsa <jo...@redhat.com> wrote: > > > > On Thu, Apr 08, 2021 at 04:39:33PM +0000, Song Liu wrote: > >> > >> > >>> On Apr 8, 2021, at 4:47 AM, Jiri Olsa <jo...@redhat.com> wrote: > >>> > >>> On Tue, Apr 06, 2021 at 05:36:01PM -0700, Song Liu wrote: > >>>> Currently, to use BPF to aggregate perf event counters, the user uses > >>>> --bpf-counters option. Enable "use bpf by default" events with a config > >>>> option, stat.bpf-counter-events. This is limited to hardware events in > >>>> evsel__hw_names. > >>>> > >>>> This also enables mixed BPF event and regular event in the same sesssion. > >>>> For example: > >>>> > >>>> perf config stat.bpf-counter-events=instructions > >>>> perf stat -e instructions,cs > >>>> > >>> > >>> so if we are mixing events now, how about uing modifier for bpf counters, > >>> instead of configuring .perfconfig list we could use: > >>> > >>> perf stat -e instructions:b,cs > >>> > >>> thoughts? > >>> > >>> the change below adds 'b' modifier and sets 'evsel::bpf_counter', > >>> feel free to use it > >> > >> I think we will need both 'b' modifier and .perfconfig configuration. > >> For systems with BPF-managed perf events running in the background, > > > > hum, I'm not sure I understand what that means.. you mean there > > are tools that run perf stat so you don't want to change them? > > We have tools that do perf_event_open(). I will change them to use > BPF managed perf events for "cycles" and "instructions". Since these > tools are running 24/7, perf-stat on the system should use BPF managed > "cycles" and "instructions" by default.
well if you are already changing the tools why not change them to add modifier.. but I don't mind adding that .perfconfig stuff if you need that > > > > >> .perfconfig makes sure perf-stat sessions will share PMCs with these > >> background monitoring tools. 'b' modifier, on the other hand, is useful > >> when the user knows there is opportunity to share the PMCs. > >> > >> Does this make sense? > > > > if there's reason for that then sure.. but let's not limit that just > > on HARDWARE events only.. there are RAW events with the same demand > > for this feature.. why don't we let user define any event for this? > > I haven't found a good way to config RAW events. I guess RAW events > could use 'b' modifier? any event uing the pmu notation like cpu/instructions/ we can allow any event to be BPF-managed, right? IIUC we don't care, the code will work with any event jirka
