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| author | Mel Gorman <mgorman@suse.de> | 2014-01-21 15:51:03 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-01-21 16:19:48 -0800 |
| commit | 286549dcaf4f128cb04f0ad56dfb677d7d19b500 (patch) | |
| tree | b59153c8b9a43c4891c16704e78b53e9baaf7de6 /kernel/sched | |
| parent | 64a9a34e22896dad430e21a28ad8cb00a756fefc (diff) | |
| download | linux-286549dcaf4f128cb04f0ad56dfb677d7d19b500.tar.bz2 | |
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/sched')
| -rw-r--r-- | kernel/sched/core.c | 2 | ||||
| -rw-r--r-- | kernel/sched/fair.c | 6 |
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); out: @@ -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)); put_task_struct(env.best_task); return ret; } |