Messages in this thread | ![/](/images/icornerl.gif) | | Subject | Re: [PATCH] sched/fair: merge same code in enqueue_task_fair | From | Tim Chen <> | Date | Mon, 11 Dec 2023 14:22:07 -0800 |
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On Sun, 2023-12-10 at 17:21 +0800, WangJinchao wrote: > 1. The code below is duplicated in two for loops and need to be > consolidated > 2. Fix the bug where a se's on_rq is true but its parent is not
In the current code, If a se is already on a rq, all the parents would have already been on rq too. I don't think there's a case where se's on_rq and parent is not for the current code before your patch. Otherwise the child would never get scheduled. I don't think we have seen such bug being reported.
> > ```c > cfs_rq->h_nr_running++; > cfs_rq->idle_h_nr_running += idle_h_nr_running; > > if (cfs_rq_is_idle(cfs_rq)) > idle_h_nr_running = 1; > > /* end evaluation on encountering a throttled cfs_rq */ > if (cfs_rq_throttled(cfs_rq)) > goto enqueue_throttle; > ``` > > Signed-off-by: WangJinchao <wangjinchao@xfusion.com> > --- > kernel/sched/fair.c | 31 ++++++++----------------------- > 1 file changed, 8 insertions(+), 23 deletions(-) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index d7a3c63a2171..e1373bfd4f2e 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -6681,30 +6681,15 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags) > cpufreq_update_util(rq, SCHED_CPUFREQ_IOWAIT); > > for_each_sched_entity(se) { > - if (se->on_rq) > - break; > cfs_rq = cfs_rq_of(se); > - enqueue_entity(cfs_rq, se, flags); > - > - cfs_rq->h_nr_running++; > - cfs_rq->idle_h_nr_running += idle_h_nr_running; > - > - if (cfs_rq_is_idle(cfs_rq)) > - idle_h_nr_running = 1; > - > - /* end evaluation on encountering a throttled cfs_rq */ > - if (cfs_rq_throttled(cfs_rq)) > - goto enqueue_throttle; > - > - flags = ENQUEUE_WAKEUP; > - } > - > - for_each_sched_entity(se) { > - cfs_rq = cfs_rq_of(se); > - > - update_load_avg(cfs_rq, se, UPDATE_TG); > - se_update_runnable(se); > - update_cfs_group(se); > + if (se->on_rq) { > + update_load_avg(cfs_rq, se, UPDATE_TG); > + se_update_runnable(se); > + update_cfs_group(se); > + } else { > + enqueue_entity(cfs_rq, se, flags); > + flags = ENQUEUE_WAKEUP; > + }
The code change looks like a reasonable simplification. Logic is the same as the old code, assuming that once a se's on_rq flag is true, all its parents are too.
Thanks.
Tim
> > cfs_rq->h_nr_running++; > cfs_rq->idle_h_nr_running += idle_h_nr_running;
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