The trace event key load is mapped to:
(1) load : cfs_rq->tg->load_avg
The cfs_rq owned by the task_group is used as the only parameter for the
trace event because it has a reference to the taskgroup and the cpu.
Using the taskgroup as a parameter instead would require the cpu as a
second parameter. A task_group is global and not per-cpu data. The cpu
key only tells on which cpu the value was gathered.
The following list shows examples of the key=value pairs for:
(1) a task group:
cpu=1 path=/tg1/tg11/tg111 id=4 load=517
(2) an autogroup:
cpu=1 path=/autogroup-10 id=0 load=1050
We don't maintain a load signal for a root task group.
The trace event is only defined if cfs group scheduling support
(CONFIG_FAIR_GROUP_SCHED) is enabled.
Signed-off-by: Dietmar Eggemann <dietmar.eggem...@arm.com>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Ingo Molnar <mi...@kernel.org>
Cc: Steven Rostedt <rost...@goodmis.org>
---
include/trace/events/sched.h | 31 +++++++++++++++++++++++++++++++
kernel/sched/fair.c | 2 ++
2 files changed, 33 insertions(+)
diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h
index 647cfaf528fd..3fe0092176f8 100644
--- a/include/trace/events/sched.h
+++ b/include/trace/events/sched.h
@@ -673,6 +673,37 @@ TRACE_EVENT(sched_load_se,
__entry->cpu, __get_str(path), __entry->id, __entry->comm,
__entry->pid, __entry->load, __entry->util)
);
+
+/*
+ * Tracepoint for task_group load tracking:
+ */
+#ifdef CONFIG_FAIR_GROUP_SCHED
+TRACE_EVENT(sched_load_tg,
+
+ TP_PROTO(struct cfs_rq *cfs_rq),
+
+ TP_ARGS(cfs_rq),
+
+ TP_STRUCT__entry(
+ __field( int, cpu )
+ __dynamic_array(char, path,
+ __trace_sched_path(cfs_rq, NULL, 0) )
+ __field( int, id )
+ __field( long, load )
+ ),
+
+ TP_fast_assign(
+ __entry->cpu = cfs_rq->rq->cpu;
+ __trace_sched_path(cfs_rq, __get_dynamic_array(path),
+ __get_dynamic_array_len(path));
+ __entry->id = cfs_rq->tg->css.id;
+ __entry->load = atomic_long_read(&cfs_rq->tg->load_avg);
+ ),
+
+ TP_printk("cpu=%d path=%s id=%d load=%ld", __entry->cpu,
+ __get_str(path), __entry->id, __entry->load)
+);
+#endif /* CONFIG_FAIR_GROUP_SCHED */
#endif /* CONFIG_SMP */
#endif /* _TRACE_SCHED_H */
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index d1dcb19f5b55..dbe2d5ef8b9e 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -2997,6 +2997,8 @@ static inline void update_tg_load_avg(struct cfs_rq
*cfs_rq, int force)
atomic_long_add(delta, &cfs_rq->tg->load_avg);
cfs_rq->tg_load_avg_contrib = cfs_rq->avg.load_avg;
}
+
+ trace_sched_load_tg(cfs_rq);
}
/*
--
2.11.0
