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authorPaul Turner <pjt@google.com>2011-07-21 09:43:38 -0700
committerIngo Molnar <mingo@elte.hu>2011-08-14 12:03:44 +0200
commit8cb120d3e41a0464a559d639d519cef563717a4e (patch)
tree4d17ae0d3d9a18cb502e5d098bd48b7436620754 /kernel/sched.c
parent5238cdd3873e67a98b28c1161d65d2a615c320a3 (diff)
sched: Migrate throttled tasks on HOTPLUG
Throttled tasks are invisisble to cpu-offline since they are not eligible for selection by pick_next_task(). The regular 'escape' path for a thread that is blocked at offline is via ttwu->select_task_rq, however this will not handle a throttled group since there are no individual thread wakeups on an unthrottle. Resolve this by unthrottling offline cpus so that threads can be migrated. Signed-off-by: Paul Turner <pjt@google.com> Reviewed-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/20110721184757.989000590@google.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/sched.c')
-rw-r--r--kernel/sched.c27
1 files changed, 27 insertions, 0 deletions
diff --git a/kernel/sched.c b/kernel/sched.c
index 5db05f6fb47..397317248dd 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -6335,6 +6335,30 @@ static void calc_global_load_remove(struct rq *rq)
rq->calc_load_active = 0;
}
+#ifdef CONFIG_CFS_BANDWIDTH
+static void unthrottle_offline_cfs_rqs(struct rq *rq)
+{
+ struct cfs_rq *cfs_rq;
+
+ for_each_leaf_cfs_rq(rq, cfs_rq) {
+ struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
+
+ if (!cfs_rq->runtime_enabled)
+ continue;
+
+ /*
+ * clock_task is not advancing so we just need to make sure
+ * there's some valid quota amount
+ */
+ cfs_rq->runtime_remaining = cfs_b->quota;
+ if (cfs_rq_throttled(cfs_rq))
+ unthrottle_cfs_rq(cfs_rq);
+ }
+}
+#else
+static void unthrottle_offline_cfs_rqs(struct rq *rq) {}
+#endif
+
/*
* Migrate all tasks from the rq, sleeping tasks will be migrated by
* try_to_wake_up()->select_task_rq().
@@ -6360,6 +6384,9 @@ static void migrate_tasks(unsigned int dead_cpu)
*/
rq->stop = NULL;
+ /* Ensure any throttled groups are reachable by pick_next_task */
+ unthrottle_offline_cfs_rqs(rq);
+
for ( ; ; ) {
/*
* There's this thread running, bail when that's the only