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.
jirka
