diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2017-09-07 17:03:50 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2017-09-12 17:41:03 +0200 |
| commit | 2800486ee34825d954f64c6f98037daea328f121 (patch) | |
| tree | b734003f0085ce39c7688259c7aeb6617ccff6e4 | |
| parent | 46123355af729514e6fa8b8a9dd1e645e61a6466 (diff) | |
sched/fair: Avoid newidle balance for !active CPUs
On CPU hot unplug, when parking the last kthread we'll try and
schedule into idle to kill the CPU. This last schedule can (and does)
trigger newidle balance because at this point the sched domains are
still up because of commit:
77d1dfda0e79 ("sched/topology, cpuset: Avoid spurious/wrong domain rebuilds")
Obviously pulling tasks to an already offline CPU is a bad idea, and
all balancing operations _should_ be subject to cpu_active_mask, make
it so.
Reported-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Fixes: 77d1dfda0e79 ("sched/topology, cpuset: Avoid spurious/wrong domain rebuilds")
Link: http://lkml.kernel.org/r/20170907150613.994135806@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
| -rw-r--r-- | kernel/sched/fair.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 8415d1ec2b84..3bcea40d3029 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -8448,6 +8448,12 @@ static int idle_balance(struct rq *this_rq, struct rq_flags *rf) this_rq->idle_stamp = rq_clock(this_rq); /* + * Do not pull tasks towards !active CPUs... + */ + if (!cpu_active(this_cpu)) + return 0; + + /* * This is OK, because current is on_cpu, which avoids it being picked * for load-balance and preemption/IRQs are still disabled avoiding * further scheduler activity on it and we're being very careful to |