The idle load balancing registration path assumes that we only stop the tick when the CPU is idle, ignoring the nohz full case. As a result, a nohz full CPU that is running a task may be chosen to perform idle load balancing.
Lets make sure that only CPUs in dynticks idle mode can be picked as idle load balancers. Signed-off-by: Frederic Weisbecker <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Rik van Riel <[email protected]> Cc: Peter Zijlstra <[email protected]> --- kernel/time/tick-sched.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 1c9a508..77c3be5 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -785,7 +785,6 @@ static ktime_t tick_nohz_stop_sched_tick(struct tick_sched *ts, * the scheduler tick in nohz_restart_sched_tick. */ if (!ts->tick_stopped) { - nohz_balance_enter_idle(cpu); calc_load_nohz_start(); cpu_load_update_nohz_start(); @@ -938,8 +937,10 @@ static void __tick_nohz_idle_enter(struct tick_sched *ts) ts->idle_expires = expires; } - if (!was_stopped && ts->tick_stopped) + if (!was_stopped && ts->tick_stopped) { ts->idle_jiffies = ts->last_jiffies; + nohz_balance_enter_idle(cpu); + } } } -- 2.7.4
