sched: Add a timer to handle CFS bandwidth refresh
This patch adds a per-task_group timer which handles the refresh of the global
CFS bandwidth pool.
Since the RT pool is using a similar timer there's some small refactoring to
share this support.
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/20110721184757.277271273@google.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 9502aa8..af73a8a 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -1284,9 +1284,16 @@
raw_spin_lock(&cfs_b->lock);
if (cfs_b->quota == RUNTIME_INF)
amount = min_amount;
- else if (cfs_b->runtime > 0) {
- amount = min(cfs_b->runtime, min_amount);
- cfs_b->runtime -= amount;
+ else {
+ /* ensure bandwidth timer remains active under consumption */
+ if (!cfs_b->timer_active)
+ __start_cfs_bandwidth(cfs_b);
+
+ if (cfs_b->runtime > 0) {
+ amount = min(cfs_b->runtime, min_amount);
+ cfs_b->runtime -= amount;
+ cfs_b->idle = 0;
+ }
}
raw_spin_unlock(&cfs_b->lock);
@@ -1315,6 +1322,33 @@
__account_cfs_rq_runtime(cfs_rq, delta_exec);
}
+/*
+ * Responsible for refilling a task_group's bandwidth and unthrottling its
+ * cfs_rqs as appropriate. If there has been no activity within the last
+ * period the timer is deactivated until scheduling resumes; cfs_b->idle is
+ * used to track this state.
+ */
+static int do_sched_cfs_period_timer(struct cfs_bandwidth *cfs_b, int overrun)
+{
+ int idle = 1;
+
+ raw_spin_lock(&cfs_b->lock);
+ /* no need to continue the timer with no bandwidth constraint */
+ if (cfs_b->quota == RUNTIME_INF)
+ goto out_unlock;
+
+ idle = cfs_b->idle;
+ cfs_b->runtime = cfs_b->quota;
+
+ /* mark as potentially idle for the upcoming period */
+ cfs_b->idle = 1;
+out_unlock:
+ if (idle)
+ cfs_b->timer_active = 0;
+ raw_spin_unlock(&cfs_b->lock);
+
+ return idle;
+}
#else
static void account_cfs_rq_runtime(struct cfs_rq *cfs_rq,
unsigned long delta_exec) {}