Commit-ID: ea16f0ea6c3dc9e1aa083bd3d1792ba02860526e Gitweb: https://git.kernel.org/tip/ea16f0ea6c3dc9e1aa083bd3d1792ba02860526e Author: Brendan Jackman <[email protected]> AuthorDate: Thu, 5 Oct 2017 11:55:51 +0100 Committer: Ingo Molnar <[email protected]> CommitDate: Tue, 10 Oct 2017 11:45:31 +0200
sched/fair: Sync task util before slow-path wakeup We use task_util() in find_idlest_group() via capacity_spare_wake(). This task_util() updated in wake_cap(). However wake_cap() is not the only reason for ending up in find_idlest_group() - we could have been sent there by wake_wide(). So explicitly sync the task util with prev_cpu when we are about to head to find_idlest_group(). We could simply do this at the beginning of select_task_rq_fair() (i.e. irrespective of whether we're heading to select_idle_sibling() or find_idlest_group() & co), but I didn't want to slow down the select_idle_sibling() path more than necessary. Don't do this during fork balancing, we won't need the task_util and we'd just clobber the last_update_time, which is supposed to be 0. Signed-off-by: Brendan Jackman <[email protected]> Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Cc: Andres Oportus <[email protected]> Cc: Dietmar Eggemann <[email protected]> Cc: Joel Fernandes <[email protected]> Cc: Josef Bacik <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Mike Galbraith <[email protected]> Cc: Morten Rasmussen <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Vincent Guittot <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]> --- kernel/sched/fair.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index cc0bfb0..c04a425 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6263,8 +6263,17 @@ select_task_rq_fair(struct task_struct *p, int prev_cpu, int sd_flag, int wake_f new_cpu = cpu; } + if (sd && !(sd_flag & SD_BALANCE_FORK)) { + /* + * We're going to need the task's util for capacity_spare_wake + * in find_idlest_group. Sync it up to prev_cpu's + * last_update_time. + */ + sync_entity_load_avg(&p->se); + } + if (!sd) { - pick_cpu: +pick_cpu: if (sd_flag & SD_BALANCE_WAKE) /* XXX always ? */ new_cpu = select_idle_sibling(p, prev_cpu, new_cpu);
