From fa853c4b839ece9cd589e8858819240933cc4d78 Mon Sep 17 00:00:00 2001 From: Song Liu Date: Tue, 29 Dec 2020 13:42:14 -0800 Subject: perf stat: Enable counting events for BPF programs 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 a common interface that uses BPF programs/maps to count perf events. Committer notes: Removed all but bpf_counter.h includes from evsel.h, not needed at all. Also BPF map lookups for PERCPU_ARRAYs need to have as its value receive buffer passed to the kernel libbpf_num_possible_cpus() entries, not evsel__nr_cpus(evsel), as the former uses /sys/devices/system/cpu/possible while the later uses /sys/devices/system/cpu/online, which may be less than the 'possible' number making the bpf map lookup overwrite memory and cause hard to debug memory corruption. We need to continue using evsel__nr_cpus(evsel) when accessing the perf_counts array tho, not to overwrite another are of memory :-) Signed-off-by: Song Liu Tested-by: Arnaldo Carvalho de Melo Link: https://lore.kernel.org/lkml/20210120163031.GU12699@kernel.org/ Acked-by: Namhyung Kim Cc: Alexander Shishkin Cc: Jiri Olsa Cc: Mark Rutland Cc: Peter Zijlstra Cc: kernel-team@fb.com Link: http://lore.kernel.org/lkml/20201229214214.3413833-4-songliubraving@fb.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/target.h | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'tools/perf/util/target.h') diff --git a/tools/perf/util/target.h b/tools/perf/util/target.h index 6ef01a83b24e..f132c6c2eef8 100644 --- a/tools/perf/util/target.h +++ b/tools/perf/util/target.h @@ -10,6 +10,7 @@ struct target { const char *tid; const char *cpu_list; const char *uid_str; + const char *bpf_str; uid_t uid; bool system_wide; bool uses_mmap; @@ -36,6 +37,10 @@ enum target_errno { TARGET_ERRNO__PID_OVERRIDE_SYSTEM, TARGET_ERRNO__UID_OVERRIDE_SYSTEM, TARGET_ERRNO__SYSTEM_OVERRIDE_THREAD, + TARGET_ERRNO__BPF_OVERRIDE_CPU, + TARGET_ERRNO__BPF_OVERRIDE_PID, + TARGET_ERRNO__BPF_OVERRIDE_UID, + TARGET_ERRNO__BPF_OVERRIDE_THREAD, /* for target__parse_uid() */ TARGET_ERRNO__INVALID_UID, @@ -59,6 +64,11 @@ static inline bool target__has_cpu(struct target *target) return target->system_wide || target->cpu_list; } +static inline bool target__has_bpf(struct target *target) +{ + return target->bpf_str; +} + static inline bool target__none(struct target *target) { return !target__has_task(target) && !target__has_cpu(target); -- cgit v1.2.3