@@ -17,6 +17,7 @@
#include "bpf_skel/off_cpu.skel.h"
#define MAX_STACKS 32
+#define MAX_PROC 4096
/* we don't need actual timestamp, just want to put the samples at last */
#define OFF_CPU_TIMESTAMP (~0ull << 32)
@@ -164,10 +165,16 @@ int off_cpu_prepare(struct evlist *evlist, struct target *target,
ntasks++;
}
+
+ if (ntasks < MAX_PROC)
+ ntasks = MAX_PROC;
+
bpf_map__set_max_entries(skel->maps.task_filter, ntasks);
} else if (target__has_task(target)) {
ntasks = perf_thread_map__nr(evlist->core.threads);
bpf_map__set_max_entries(skel->maps.task_filter, ntasks);
+ } else if (target__none(target)) {
+ bpf_map__set_max_entries(skel->maps.task_filter, MAX_PROC);
}
if (evlist__first(evlist)->cgrp) {
@@ -12,6 +12,9 @@
#define TASK_INTERRUPTIBLE 0x0001
#define TASK_UNINTERRUPTIBLE 0x0002
+/* create a new thread */
+#define CLONE_THREAD 0x10000
+
#define MAX_STACKS 32
#define MAX_ENTRIES 102400
@@ -220,6 +223,33 @@ static int off_cpu_stat(u64 *ctx, struct task_struct *prev,
return 0;
}
+SEC("tp_btf/task_newtask")
+int on_newtask(u64 *ctx)
+{
+ struct task_struct *task;
+ u64 clone_flags;
+ u32 pid;
+ u8 val = 1;
+
+ if (!uses_tgid)
+ return 0;
+
+ task = (struct task_struct *)bpf_get_current_task();
+
+ pid = BPF_CORE_READ(task, tgid);
+ if (!bpf_map_lookup_elem(&task_filter, &pid))
+ return 0;
+
+ task = (struct task_struct *)ctx[0];
+ clone_flags = ctx[1];
+
+ pid = task->tgid;
+ if (!(clone_flags & CLONE_THREAD))
+ bpf_map_update_elem(&task_filter, &pid, &val, BPF_NOEXIST);
+
+ return 0;
+}
+
SEC("tp_btf/sched_switch")
int on_switch(u64 *ctx)
{
When -p option used or a workload is given, it needs to handle child processes. The perf_event can inherit those task events automatically. We can add a new BPF program in task_newtask tracepoint to track child processes. Before: $ sudo perf record --off-cpu -- perf bench sched messaging $ sudo perf report --stat | grep -A1 offcpu offcpu-time stats: SAMPLE events: 1 After: $ sudo perf record -a --off-cpu -- perf bench sched messaging $ sudo perf report --stat | grep -A1 offcpu offcpu-time stats: SAMPLE events: 856 Signed-off-by: Namhyung Kim <namhyung@kernel.org> --- tools/perf/util/bpf_off_cpu.c | 7 ++++++ tools/perf/util/bpf_skel/off_cpu.bpf.c | 30 ++++++++++++++++++++++++++ 2 files changed, 37 insertions(+)