Messages in this thread |  | | Date | Tue, 29 Dec 2020 12:15:04 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [PATCH v6 3/4] perf-stat: enable counting events for BPF programs |
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Em Mon, Dec 28, 2020 at 11:43:25PM +0000, Song Liu escreveu: > > > > On Dec 28, 2020, at 12:11 PM, Arnaldo Carvalho de Melo <acme@kernel.org> wrote: > > > > Em Mon, Dec 28, 2020 at 09:40:53AM -0800, Song Liu escreveu: > >> 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. > > > > Segfaulting here: > > > > [root@five ~]# bpftool prog | grep tracepoint > > 110: tracepoint name syscall_unaugme tag 57cd311f2e27366b gpl > > 111: tracepoint name sys_enter_conne tag 3555418ac9476139 gpl > > 112: tracepoint name sys_enter_sendt tag bc7fcadbaf7b8145 gpl > > 113: tracepoint name sys_enter_open tag 0e59c3ac2bea5280 gpl > > 114: tracepoint name sys_enter_opena tag 0baf443610f59837 gpl > > 115: tracepoint name sys_enter_renam tag 24664e4aca62d7fa gpl > > 116: tracepoint name sys_enter_renam tag 20093e51a8634ebb gpl > > 117: tracepoint name sys_enter tag 0bc3fc9d11754ba1 gpl > > 118: tracepoint name sys_exit tag 29c7ae234d79bd5c gpl > > [root@five ~]# > > [root@five ~]# gdb perf > > GNU gdb (GDB) Fedora 10.1-2.fc33 > > Reading symbols from perf... > > (gdb) run stat -e instructions,cycles -b 113 -I 1000 > > Starting program: /root/bin/perf stat -e instructions,cycles -b 113 -I 1000 > > [Thread debugging using libthread_db enabled] > > Using host libthread_db library "/lib64/libthread_db.so.1". > > libbpf: elf: skipping unrecognized data section(9) .eh_frame > > libbpf: elf: skipping relo section(15) .rel.eh_frame for section(9) .eh_frame > > libbpf: elf: skipping unrecognized data section(9) .eh_frame > > libbpf: elf: skipping relo section(15) .rel.eh_frame for section(9) .eh_frame > > > > Program received signal SIGSEGV, Segmentation fault. > > 0x000000000058d55b in bpf_program_profiler__read (evsel=0xc612c0) at util/bpf_counter.c:217 > > 217 reading_map_fd = bpf_map__fd(skel->maps.accum_readings); > > (gdb) bt > > #0 0x000000000058d55b in bpf_program_profiler__read (evsel=0xc612c0) at util/bpf_counter.c:217 > > #1 0x0000000000000000 in ?? () > > (gdb) > > > > [acme@five perf]$ clang -v |& head -2 > > clang version 11.0.0 (Fedora 11.0.0-2.fc33) > > Target: x86_64-unknown-linux-gnu > > [acme@five perf]$ > > > > Do you need any extra info? > > Hmm... I am not able to reproduce this. I am trying to setup an environment similar > to fc33 (clang 11, etc.). Does this segfault every time, and on all programs?
I'll try it with a BPF proggie attached to a kprobes, but here is something else I noticed:
[root@five perf]# export PYTHONPATH=/tmp/build/perf/python [root@five perf]# tools/perf/python/twatch.py Traceback (most recent call last): File "/home/acme/git/perf/tools/perf/python/twatch.py", line 9, in <module> import perf ImportError: /tmp/build/perf/python/perf.cpython-39-x86_64-linux-gnu.so: undefined symbol: bpf_counter__destroy [root@five perf]# perf test python 19: 'import perf' in python : FAILED! [root@five perf]# perf test -v python 19: 'import perf' in python : --- start --- test child forked, pid 3198864 python usage test: "echo "import sys ; sys.path.append('/tmp/build/perf/python'); import perf" | '/usr/bin/python3' " Traceback (most recent call last): File "<stdin>", line 1, in <module> ImportError: /tmp/build/perf/python/perf.cpython-39-x86_64-linux-gnu.so: undefined symbol: bpf_counter__destroy test child finished with -1 ---- end ---- 'import perf' in python: FAILED! [root@five perf]#
This should be trivial, I hope, just add the new object file to tools/perf/util/python-ext-sources, then do a 'perf test python', if it fails, use 'perf test -v python' to see what is preventing the python binding from loading.
- Arnaldo
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