path: root/kernel
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authorMel Gorman <mgorman@suse.de>2014-01-21 15:51:03 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2014-01-21 16:19:48 -0800
commit286549dcaf4f128cb04f0ad56dfb677d7d19b500 (patch)
treeb59153c8b9a43c4891c16704e78b53e9baaf7de6 /kernel
parent64a9a34e22896dad430e21a28ad8cb00a756fefc (diff)
sched: add tracepoints related to NUMA task migration
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. [akpm@linux-foundation.org: remove semicolon-after-if, repair coding-style] Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Alex Thorlton <athorlton@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel')
2 files changed, 7 insertions, 1 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 36c951b7eef8..5ae36cc11fe5 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);
@@ -4603,6 +4604,7 @@ 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 b24b6cfde9aa..867b0a4b0893 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -1250,11 +1250,15 @@ 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);
+ ret = migrate_task_to(p, env.best_cpu);
+ if (ret != 0)
+ trace_sched_stick_numa(p, env.src_cpu, env.best_cpu);
return ret;
ret = migrate_swap(p, env.best_task);
+ if (ret != 0)
+ trace_sched_stick_numa(p, env.src_cpu, task_cpu(env.best_task));
return ret;

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