Messages in this thread | | | Subject | Re: [PATCH 3/8] sched,fair: redefine runnable_load_avg as the sum of task_h_load | From | Dietmar Eggemann <> | Date | Wed, 26 Jun 2019 16:34:31 +0200 |
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On 6/12/19 9:32 PM, Rik van Riel wrote: > The runnable_load magic is used to quickly propagate information about > runnable tasks up the hierarchy of runqueues. lhen switching to a flat
Looks like here is some information missing.
> runqueue, that no longer works. > > Redefine the CPU cfs_rq runnable_load_avg to be the sum of task_h_loads > of the runnable tasks. This provides enough information to the load > balancer. > > The runnable_load_avg of the cgroup cfs_rqs does not appear to be > used for anything, so don't bother calculating those. > > This removes one of the things that the code currently traverses the > cgroup hierarchy for, and getting rid of it brings us one step closer > to a flat runqueue for the CPU controller. > > Signed-off-by: Rik van Riel <riel@surriel.com> > --- > include/linux/sched.h | 3 +- > kernel/sched/core.c | 2 - > kernel/sched/debug.c | 1 + > kernel/sched/fair.c | 125 +++++++++++++----------------------------- > kernel/sched/pelt.c | 49 ++++++----------- > kernel/sched/sched.h | 6 -- > 6 files changed, 55 insertions(+), 131 deletions(-) > > diff --git a/include/linux/sched.h b/include/linux/sched.h > index 11837410690f..f5bb6948e40c 100644 > --- a/include/linux/sched.h > +++ b/include/linux/sched.h > @@ -391,7 +391,6 @@ struct util_est { > struct sched_avg { > u64 last_update_time; > u64 load_sum; > - u64 runnable_load_sum; > u32 util_sum; > u32 period_contrib; > unsigned long load_avg;
Could you not also remove runnable_load_avg from struct sched_avg and put it into the struct cfs_rq directly. The signal has nothing to to with PELT anymore and se don't have to carry it. You only need it for the root cfs_rq's but it's at least better than having it still for all se's as well.
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> @@ -2767,20 +2765,39 @@ account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se) > static inline void > enqueue_runnable_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) > { > - cfs_rq->runnable_weight += se->runnable_weight; > + if (entity_is_task(se)) { > + struct cfs_rq *cpu_cfs_rq = &cfs_rq->rq->cfs;
There are a couple of comments in fair.c referring to this cfs_rq as the root cfs_rq, rather the cpu cfs_rq. IMHO, easier to read if we stick to one name (root_cfs_rq vs. cpu_cfs_rq).
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