From: Frederic Weisbecker <fweis...@gmail.com>
Because the sched_class::put_prev_task() callback of rt and fair
classes are referring to the rq clock to update their runtime
statistics. A CPU running in tickless mode may carry a stale value.
We need to update it there.
Signed-off-by: Frederic Weisbecker <fweis...@gmail.com>
Cc: Alessio Igor Bogani <abog...@kernel.org>
Cc: Andrew Morton <a...@linux-foundation.org>
Cc: Avi Kivity <a...@redhat.com>
Cc: Chris Metcalf <cmetc...@tilera.com>
Cc: Christoph Lameter <c...@linux.com>
Cc: Daniel Lezcano <daniel.lezc...@linaro.org>
Cc: Geoff Levand <ge...@infradead.org>
Cc: Gilad Ben Yossef <gi...@benyossef.com>
Cc: Hakan Akkan <hakanak...@gmail.com>
Cc: Ingo Molnar <mi...@kernel.org>
Cc: Kevin Hilman <khil...@ti.com>
Cc: Max Krasnyansky <m...@qualcomm.com>
Cc: Paul E. McKenney <paul...@linux.vnet.ibm.com>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Stephen Hemminger <shemmin...@vyatta.com>
Cc: Steven Rostedt <rost...@goodmis.org>
Cc: Sven-Thorsten Dietrich <thebigcorporat...@gmail.com>
Cc: Thomas Gleixner <t...@linutronix.de>
---
kernel/sched/core.c | 6 ++++++
kernel/sched/sched.h | 6 ++++++
2 files changed, 12 insertions(+)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 783d5e4..f0fa54d 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -4851,6 +4851,12 @@ static void migrate_tasks(unsigned int dead_cpu)
*/
rq->stop = NULL;
+ /*
+ * ->put_prev_task() need to have an up-to-date value
+ * of rq->clock[_task]
+ */
+ update_nohz_rq_clock(rq);
+
for ( ; ; ) {
/*
* There's this thread running, bail when that's the only
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index c6cd9ec..1956494 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -948,6 +948,12 @@ static inline void dec_nr_running(struct rq *rq)
extern void update_rq_clock(struct rq *rq);
+static inline void update_nohz_rq_clock(struct rq *rq)
+{
+ if (cpuset_cpu_adaptive_nohz(cpu_of(rq)))
+ update_rq_clock(rq);
+}
+
extern void activate_task(struct rq *rq, struct task_struct *p, int flags);
extern void deactivate_task(struct rq *rq, struct task_struct *p, int flags);
--
1.7.10.4
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