This patch adds three tracepoints
o trace_sched_move_numa when a task is moved to a node
o trace_sched_swap_numa when a task is swapped with another task
o trace_sched_stick_numa when a numa-related migration fails
The tracepoints allow the NUMA scheduler activity to be monitored and the
following high-level metrics can be calculated
o NUMA migrated stuck nr trace_sched_stick_numa
o NUMA migrated idle nr trace_sched_move_numa
o NUMA migrated swapped nr trace_sched_swap_numa
o NUMA local swapped trace_sched_swap_numa src_nid == dst_nid (should never
happen)
o NUMA remote swapped trace_sched_swap_numa src_nid != dst_nid (should ==
NUMA migrated swapped)
o NUMA group swapped trace_sched_swap_numa src_ngid == dst_ngid
Maybe a small number of these are acceptable
but a high number would be a major surprise.
It would be even worse if bounces are frequent.
o NUMA avg task migs. Average number of migrations for tasks
o NUMA stddev task mig Self-explanatory
o NUMA max task migs. Maximum number of migrations for a single task
In general the intent of the tracepoints is to help diagnose problems
where automatic NUMA balancing appears to be doing an excessive amount of
useless work.
Signed-off-by: Mel Gorman <mgor...@suse.de>
---
include/trace/events/sched.h | 68 ++++++++++++++++++++++++++++++++++++++++----
kernel/sched/core.c | 2 ++
kernel/sched/fair.c | 6 ++--
3 files changed, 69 insertions(+), 7 deletions(-)
diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h
index cf1694c..f0c54e3 100644
--- a/include/trace/events/sched.h
+++ b/include/trace/events/sched.h
@@ -443,11 +443,7 @@ TRACE_EVENT(sched_process_hang,
);
#endif /* CONFIG_DETECT_HUNG_TASK */
-/*
- * 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_task,
+DECLARE_EVENT_CLASS(sched_move_task_template,
TP_PROTO(struct task_struct *tsk, int src_cpu, int dst_cpu),
@@ -478,6 +474,68 @@ TRACE_EVENT(sched_move_task,
__entry->src_cpu, __entry->src_nid,
__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_task,
+ TP_PROTO(struct task_struct *tsk, int src_cpu, int dst_cpu),
+
+ TP_ARGS(tsk, src_cpu, dst_cpu)
+);
+
+DEFINE_EVENT(sched_move_task_template, sched_move_numa,
+ TP_PROTO(struct task_struct *tsk, int src_cpu, int dst_cpu),
+
+ TP_ARGS(tsk, src_cpu, 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(tsk, src_cpu, dst_cpu)
+);
+
+TRACE_EVENT(sched_swap_numa,
+
+ TP_PROTO(struct task_struct *src_tsk, int src_cpu,
+ struct task_struct *dst_tsk, int dst_cpu),
+
+ TP_ARGS(src_tsk, src_cpu, dst_tsk, 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 = task_pid_nr(dst_tsk);
+ __entry->dst_tgid = task_tgid_nr(dst_tsk);
+ __entry->dst_ngid = task_numa_group_id(dst_tsk);
+ __entry->dst_cpu = dst_cpu;
+ __entry->dst_nid = cpu_to_node(dst_cpu);
+ ),
+
+ 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)
+);
#endif /* _TRACE_SCHED_H */
/* This part must be outside protection */
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index c180860..3980110 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1108,6 +1108,7 @@ int migrate_swap(struct task_struct *cur, struct
task_struct *p)
if (!cpumask_test_cpu(arg.src_cpu, tsk_cpus_allowed(arg.dst_task)))
goto out;
+ trace_sched_swap_numa(cur, arg.src_cpu, p, arg.dst_cpu);
ret = stop_two_cpus(arg.dst_cpu, arg.src_cpu, migrate_swap_stop, &arg);
out:
@@ -4091,6 +4092,7 @@ int migrate_task_to(struct task_struct *p, int target_cpu)
/* TODO: This is not properly updating schedstats */
+ trace_sched_move_numa(p, curr_cpu, target_cpu);
return stop_one_cpu(curr_cpu, migration_cpu_stop, &arg);
}
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 41021c8..aac8c65 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -1272,11 +1272,13 @@ static int task_numa_migrate(struct task_struct *p)
p->numa_scan_period = task_scan_min(p);
if (env.best_task == NULL) {
- int ret = migrate_task_to(p, env.best_cpu);
+ if ((ret = migrate_task_to(p, env.best_cpu)) != 0)
+ trace_sched_stick_numa(p, env.src_cpu, env.best_cpu);
return ret;
}
- ret = migrate_swap(p, env.best_task);
+ if ((ret = migrate_swap(p, env.best_task)) != 0);
+ trace_sched_stick_numa(p, env.src_cpu, task_cpu(env.best_task));
put_task_struct(env.best_task);
return ret;
}
--
1.8.4
--
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