| Message ID | 20220811185456.194721-2-namhyung@kernel.org (mailing list archive) |
|---|---|
| State | Not Applicable |
| Delegated to: | BPF |
| Headers | show |
| Series | Track processes properly for perf record --off-cpu (v2) | expand |
| Context | Check | Description |
|---|---|---|
| netdev/tree_selection | success | Not a local patch |
| bpf/vmtest-bpf-next-VM_Test-1 | success | Logs for Kernel LATEST on ubuntu-latest with gcc |
| bpf/vmtest-bpf-next-VM_Test-2 | success | Logs for Kernel LATEST on ubuntu-latest with llvm-16 |
| bpf/vmtest-bpf-next-PR | success | PR summary |
| bpf/vmtest-bpf-next-VM_Test-3 | success | Logs for Kernel LATEST on z15 with gcc |
diff --git a/tools/perf/util/bpf_off_cpu.c b/tools/perf/util/bpf_off_cpu.c index f289b7713598..7dbcb025da87 100644 --- a/tools/perf/util/bpf_off_cpu.c +++ b/tools/perf/util/bpf_off_cpu.c @@ -78,6 +78,7 @@ static void off_cpu_start(void *arg) u8 val = 1; skel->bss->has_task = 1; + skel->bss->uses_tgid = 1; fd = bpf_map__fd(skel->maps.task_filter); pid = perf_thread_map__pid(evlist->core.threads, 0); bpf_map_update_elem(fd, &pid, &val, BPF_ANY); diff --git a/tools/perf/util/bpf_skel/off_cpu.bpf.c b/tools/perf/util/bpf_skel/off_cpu.bpf.c index cc6d7fd55118..143a8b7acf87 100644 --- a/tools/perf/util/bpf_skel/off_cpu.bpf.c +++ b/tools/perf/util/bpf_skel/off_cpu.bpf.c @@ -85,6 +85,7 @@ int enabled = 0; int has_cpu = 0; int has_task = 0; int has_cgroup = 0; +int uses_tgid = 0; const volatile bool has_prev_state = false; const volatile bool needs_cgroup = false; @@ -144,7 +145,12 @@ static inline int can_record(struct task_struct *t, int state) if (has_task) { __u8 *ok; - __u32 pid = t->pid; + __u32 pid; + + if (uses_tgid) + pid = t->tgid; + else + pid = t->pid; ok = bpf_map_lookup_elem(&task_filter, &pid); if (!ok)
Current task filter checks task->pid which is different for each thread. But we want to profile all the threads in the process. So let's compare process id (or thread-group id: tgid) instead. Before: $ sudo perf record --off-cpu -- perf bench sched messaging -t $ sudo perf report --stat | grep -A1 offcpu offcpu-time stats: SAMPLE events: 2 After: $ sudo perf record --off-cpu -- perf bench sched messaging -t $ sudo perf report --stat | grep -A1 offcpu offcpu-time stats: SAMPLE events: 850 Signed-off-by: Namhyung Kim <namhyung@kernel.org> --- tools/perf/util/bpf_off_cpu.c | 1 + tools/perf/util/bpf_skel/off_cpu.bpf.c | 8 +++++++- 2 files changed, 8 insertions(+), 1 deletion(-)