> On Mar 4, 2020, at 11:21 AM, Jiri Olsa <jolsa@xxxxxxxxxx> wrote:
>
> On Wed, Mar 04, 2020 at 10:07:07AM -0800, Song Liu wrote:
>> With fentry/fexit programs, it is possible to profile BPF program with
>> hardware counters. Introduce bpftool "prog profile", which measures key
>> metrics of a BPF program.
>>
>> bpftool prog profile command creates per-cpu perf events. Then it attaches
>> fentry/fexit programs to the target BPF program. The fentry program saves
>> perf event value to a map. The fexit program reads the perf event again,
>> and calculates the difference, which is the instructions/cycles used by
>> the target program.
>>
>> Example input and output:
>>
>> ./bpftool prog profile id 337 duration 3 cycles instructions llc_misses
>>
>> 4228 run_cnt
>> 3403698 cycles (84.08%)
>> 3525294 instructions # 1.04 insn per cycle (84.05%)
>> 13 llc_misses # 3.69 LLC misses per million isns (83.50%)
>
> FYI I'm in the middle of moving perf's 'events parsing' interface to libperf,
> which takes event name/s on input and returns list of perf_event_attr objects
>
> parse_events("cycles") -> ready to use 'struct perf_event_attr'
>
> You can use any event that's listed in 'perf list' command, which includes
> also all vendor (Intel/Arm/ppc..) events. It might be useful extension for
> this command.
That's great news! Thanks for the information!
Song
