diff options
| author | Vineeth Pillai <viremana@linux.microsoft.com> | 2020-11-17 18:19:38 -0500 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2021-05-12 11:43:29 +0200 |
| commit | 8039e96fcc1de30d5bcaf05da9ca2de46a800826 (patch) | |
| tree | bb88e1ba8c783a34c54be34b5c33ccc405fac444 /kernel/sched/core.c | |
| parent | sched: Add core wide task selection and scheduling (diff) | |
| download | linux-8039e96fcc1de30d5bcaf05da9ca2de46a800826.tar.gz linux-8039e96fcc1de30d5bcaf05da9ca2de46a800826.zip | |
sched/fair: Fix forced idle sibling starvation corner case
If there is only one long running local task and the sibling is
forced idle, it might not get a chance to run until a schedule
event happens on any cpu in the core.
So we check for this condition during a tick to see if a sibling
is starved and then give it a chance to schedule.
Signed-off-by: Vineeth Pillai <viremana@linux.microsoft.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Don Hiatt <dhiatt@digitalocean.com>
Tested-by: Hongyu Ning <hongyu.ning@linux.intel.com>
Tested-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/20210422123308.617407840@infradead.org
Diffstat (limited to 'kernel/sched/core.c')
| -rw-r--r-- | kernel/sched/core.c | 15 |
1 files changed, 8 insertions, 7 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index db763f42a4b0..f5e1e6f96411 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -5459,16 +5459,15 @@ pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) /* reset state */ rq->core->core_cookie = 0UL; + if (rq->core->core_forceidle) { + need_sync = true; + rq->core->core_forceidle = false; + } for_each_cpu(i, smt_mask) { struct rq *rq_i = cpu_rq(i); rq_i->core_pick = NULL; - if (rq_i->core_forceidle) { - need_sync = true; - rq_i->core_forceidle = false; - } - if (i != cpu) update_rq_clock(rq_i); } @@ -5588,8 +5587,10 @@ next_class:; if (!rq_i->core_pick) continue; - if (is_task_rq_idle(rq_i->core_pick) && rq_i->nr_running) - rq_i->core_forceidle = true; + if (is_task_rq_idle(rq_i->core_pick) && rq_i->nr_running && + !rq_i->core->core_forceidle) { + rq_i->core->core_forceidle = true; + } if (i == cpu) { rq_i->core_pick = NULL; |