Messages in this thread | | | From | Song Liu <> | Subject | Re: [PATCH v2 3/3] perf-stat: introduce config stat.bpf-counter-events | Date | Thu, 8 Apr 2021 17:28:10 +0000 |
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> On Apr 8, 2021, at 10:20 AM, Jiri Olsa <jolsa@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 <jolsa@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.
> >> .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?
Thanks, Song
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