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authorPaul Turner <pjt@google.com>2012-10-04 13:18:30 +0200
committerIngo Molnar <mingo@kernel.org>2012-10-24 10:27:23 +0200
commit0a74bef8bed18dc6889e9bc37ea1050a50c86c89 (patch)
tree9d7b66a1b7ac0b05cd9b9b093cb6d89904db8f83 /kernel
parent9ee474f55664ff63111c843099d365e7ecffb56f (diff)
downloadblackbird-op-linux-0a74bef8bed18dc6889e9bc37ea1050a50c86c89.tar.gz
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sched: Add an rq migration call-back to sched_class
Since we are now doing bottom up load accumulation we need explicit notification when a task has been re-parented so that the old hierarchy can be updated. Adds: migrate_task_rq(struct task_struct *p, int next_cpu) (The alternative is to do this out of __set_task_cpu, but it was suggested that this would be a cleaner encapsulation.) Signed-off-by: Paul Turner <pjt@google.com> Reviewed-by: Ben Segall <bsegall@google.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/20120823141506.660023400@google.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/sched/core.c2
-rw-r--r--kernel/sched/fair.c12
2 files changed, 14 insertions, 0 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 00898f1fb69e..f26860074ef2 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -952,6 +952,8 @@ void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
trace_sched_migrate_task(p, new_cpu);
if (task_cpu(p) != new_cpu) {
+ if (p->sched_class->migrate_task_rq)
+ p->sched_class->migrate_task_rq(p, new_cpu);
p->se.nr_migrations++;
perf_sw_event(PERF_COUNT_SW_CPU_MIGRATIONS, 1, NULL, 0);
}
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 83194175e841..5e602e6ba0c3 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -3047,6 +3047,17 @@ unlock:
return new_cpu;
}
+
+/*
+ * Called immediately before a task is migrated to a new cpu; task_cpu(p) and
+ * cfs_rq_of(p) references at time of call are still valid and identify the
+ * previous cpu. However, the caller only guarantees p->pi_lock is held; no
+ * other assumptions, including the state of rq->lock, should be made.
+ */
+static void
+migrate_task_rq_fair(struct task_struct *p, int next_cpu)
+{
+}
#endif /* CONFIG_SMP */
static unsigned long
@@ -5607,6 +5618,7 @@ const struct sched_class fair_sched_class = {
#ifdef CONFIG_SMP
.select_task_rq = select_task_rq_fair,
+ .migrate_task_rq = migrate_task_rq_fair,
.rq_online = rq_online_fair,
.rq_offline = rq_offline_fair,
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