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Subject[PATCH 05/11] sched/numa: Distinguish between the different task_numa_migrate failure cases
Date
sched:sched_stick_numa is meant to fire when a task is unable to migrate
to the preferred node but from the trace, it's possibile to tell the
difference between "no CPU found", "migration to idle CPU failed" and
"tasks could not be swapped". Extend the tracepoint accordingly.

Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
---
include/trace/events/sched.h | 51 +++++++++++++++++++++++++++++++++-----------
kernel/sched/fair.c | 6 +++---
2 files changed, 42 insertions(+), 15 deletions(-)

diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h
index 420e80e56e55..3d07c0af4ab8 100644
--- a/include/trace/events/sched.h
+++ b/include/trace/events/sched.h
@@ -487,7 +487,11 @@ TRACE_EVENT(sched_process_hang,
);
#endif /* CONFIG_DETECT_HUNG_TASK */

-DECLARE_EVENT_CLASS(sched_move_task_template,
+/*
+ * Tracks migration of tasks from one runqueue to another. Can be used to
+ * detect if automatic NUMA balancing is bouncing between nodes
+ */
+TRACE_EVENT(sched_move_numa,

TP_PROTO(struct task_struct *tsk, int src_cpu, int dst_cpu),

@@ -519,20 +523,43 @@ DECLARE_EVENT_CLASS(sched_move_task_template,
__entry->dst_cpu, __entry->dst_nid)
);

-/*
- * Tracks migration of tasks from one runqueue to another. Can be used to
- * detect if automatic NUMA balancing is bouncing between nodes
- */
-DEFINE_EVENT(sched_move_task_template, sched_move_numa,
- TP_PROTO(struct task_struct *tsk, int src_cpu, int dst_cpu),
+TRACE_EVENT(sched_stick_numa,

- TP_ARGS(tsk, src_cpu, dst_cpu)
-);
+ TP_PROTO(struct task_struct *src_tsk, int src_cpu, struct task_struct *dst_tsk, int dst_cpu),

-DEFINE_EVENT(sched_move_task_template, sched_stick_numa,
- TP_PROTO(struct task_struct *tsk, int src_cpu, int dst_cpu),
+ TP_ARGS(src_tsk, src_cpu, dst_tsk, dst_cpu),

- TP_ARGS(tsk, src_cpu, dst_cpu)
+ TP_STRUCT__entry(
+ __field( pid_t, src_pid )
+ __field( pid_t, src_tgid )
+ __field( pid_t, src_ngid )
+ __field( int, src_cpu )
+ __field( int, src_nid )
+ __field( pid_t, dst_pid )
+ __field( pid_t, dst_tgid )
+ __field( pid_t, dst_ngid )
+ __field( int, dst_cpu )
+ __field( int, dst_nid )
+ ),
+
+ TP_fast_assign(
+ __entry->src_pid = task_pid_nr(src_tsk);
+ __entry->src_tgid = task_tgid_nr(src_tsk);
+ __entry->src_ngid = task_numa_group_id(src_tsk);
+ __entry->src_cpu = src_cpu;
+ __entry->src_nid = cpu_to_node(src_cpu);
+ __entry->dst_pid = dst_tsk ? task_pid_nr(dst_tsk) : 0;
+ __entry->dst_tgid = dst_tsk ? task_tgid_nr(dst_tsk) : 0;
+ __entry->dst_ngid = dst_tsk ? task_numa_group_id(dst_tsk) : 0;
+ __entry->dst_cpu = dst_cpu;
+ __entry->dst_nid = dst_cpu >= 0 ? cpu_to_node(dst_cpu) : -1;
+ ),
+
+ TP_printk("src_pid=%d src_tgid=%d src_ngid=%d src_cpu=%d src_nid=%d dst_pid=%d dst_tgid=%d dst_ngid=%d dst_cpu=%d dst_nid=%d",
+ __entry->src_pid, __entry->src_tgid, __entry->src_ngid,
+ __entry->src_cpu, __entry->src_nid,
+ __entry->dst_pid, __entry->dst_tgid, __entry->dst_ngid,
+ __entry->dst_cpu, __entry->dst_nid)
);

TRACE_EVENT(sched_swap_numa,
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 4ab18fba5b82..6005ce28033b 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -1849,7 +1849,7 @@ static int task_numa_migrate(struct task_struct *p)

/* No better CPU than the current one was found. */
if (env.best_cpu == -1) {
- trace_sched_stick_numa(p, env.src_cpu, -1);
+ trace_sched_stick_numa(p, env.src_cpu, NULL, -1);
return -EAGAIN;
}

@@ -1858,7 +1858,7 @@ static int task_numa_migrate(struct task_struct *p)
ret = migrate_task_to(p, env.best_cpu);
WRITE_ONCE(best_rq->numa_migrate_on, 0);
if (ret != 0)
- trace_sched_stick_numa(p, env.src_cpu, env.best_cpu);
+ trace_sched_stick_numa(p, env.src_cpu, NULL, env.best_cpu);
return ret;
}

@@ -1866,7 +1866,7 @@ static int task_numa_migrate(struct task_struct *p)
WRITE_ONCE(best_rq->numa_migrate_on, 0);

if (ret != 0)
- trace_sched_stick_numa(p, env.src_cpu, task_cpu(env.best_task));
+ trace_sched_stick_numa(p, env.src_cpu, env.best_task, env.best_cpu);
put_task_struct(env.best_task);
return ret;
}
--
2.16.4
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