On Wed, Nov 18, 2020 at 08:50:46PM -0800, Song Liu wrote:
> Introduce perf-stat -b option, which counts events for BPF programs, like:
>
> [root@localhost ~]# ~/perf stat -e ref-cycles,cycles -b 254 -I 1000
> 1.487903822 115,200 ref-cycles
> 1.487903822 86,012 cycles
> 2.489147029 80,560 ref-cycles
> 2.489147029 73,784 cycles
> 3.490341825 60,720 ref-cycles
> 3.490341825 37,797 cycles
> 4.491540887 37,120 ref-cycles
> 4.491540887 31,963 cycles
>
> The example above counts cycles and ref-cycles of BPF program of id 254.
> This is similar to bpftool-prog-profile command, but more flexible.
>
> perf-stat -b creates per-cpu perf_event and loads fentry/fexit BPF
> programs (monitor-progs) to the target BPF program (target-prog). The
> monitor-progs read perf_event before and after the target-prog, and
> aggregate the difference in a BPF map. Then the user space reads data
> from these maps.
>
> A new struct bpf_counter is introduced to provide common interface that
> uses BPF programs/maps to count perf events.
>
> Signed-off-by: Song Liu <[email protected]>
I still need to review this deeply, but so far I'm getting this error:
# ./perf stat -b 40
libbpf: elf: skipping unrecognized data section(9) .eh_frame
libbpf: elf: skipping relo section(15) .rel.eh_frame for section(9)
.eh_frame
libbpf: XXX is not found in vmlinux BTF
libbpf: failed to load object 'bpf_prog_profiler_bpf'
libbpf: failed to load BPF skeleton 'bpf_prog_profiler_bpf': -2
libbpf: elf: skipping unrecognized data section(9) .eh_frame
libbpf: elf: skipping relo section(15) .rel.eh_frame for section(9)
.eh_frame
libbpf: XXX is not found in vmlinux BTF
libbpf: failed to load object 'bpf_prog_profiler_bpf'
libbpf: failed to load BPF skeleton 'bpf_prog_profiler_bpf': -2
libbpf: elf: skipping unrecognized data section(9) .eh_frame
libbpf: elf: skipping relo section(15) .rel.eh_frame for section(9)
.eh_frame
libbpf: XXX is not found in vmlinux BTF
libbpf: failed to load object 'bpf_prog_profiler_bpf'
libbpf: failed to load BPF skeleton 'bpf_prog_profiler_bpf': -2
libbpf: elf: skipping unrecognized data section(9) .eh_frame
libbpf: elf: skipping relo section(15) .rel.eh_frame for section(9)
.eh_frame
libbpf: XXX is not found in vmlinux BTF
libbpf: failed to load object 'bpf_prog_profiler_bpf'
libbpf: failed to load BPF skeleton 'bpf_prog_profiler_bpf': -2
libbpf: elf: skipping unrecognized data section(9) .eh_frame
libbpf: elf: skipping relo section(15) .rel.eh_frame for section(9)
.eh_frame
libbpf: XXX is not found in vmlinux BTF
libbpf: failed to load object 'bpf_prog_profiler_bpf'
libbpf: failed to load BPF skeleton 'bpf_prog_profiler_bpf': -2
libbpf: elf: skipping unrecognized data section(9) .eh_frame
libbpf: elf: skipping relo section(15) .rel.eh_frame for section(9)
.eh_frame
libbpf: XXX is not found in vmlinux BTF
libbpf: failed to load object 'bpf_prog_profiler_bpf'
libbpf: failed to load BPF skeleton 'bpf_prog_profiler_bpf': -2
libbpf: elf: skipping unrecognized data section(9) .eh_frame
libbpf: elf: skipping relo section(15) .rel.eh_frame for section(9)
.eh_frame
libbpf: XXX is not found in vmlinux BTF
libbpf: failed to load object 'bpf_prog_profiler_bpf'
libbpf: failed to load BPF skeleton 'bpf_prog_profiler_bpf': -2
libbpf: elf: skipping unrecognized data section(9) .eh_frame
libbpf: elf: skipping relo section(15) .rel.eh_frame for section(9)
.eh_frame
libbpf: XXX is not found in vmlinux BTF
libbpf: failed to load object 'bpf_prog_profiler_bpf'
libbpf: failed to load BPF skeleton 'bpf_prog_profiler_bpf': -2
libbpf: Can't get the 0th fd from program fentry_XXX: only -1 instances
libbpf: prog 'fentry_XXX': can't attach before loaded
libbpf: failed to auto-attach program 'fentry_XXX': -22
jirka
