Messages in this thread | | | Subject | Re: [PATCH 8/8] sched,fair: flatten hierarchical runqueues | From | Rik van Riel <> | Date | Fri, 28 Jun 2019 15:36:15 -0400 |
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On Fri, 2019-06-28 at 12:26 +0200, Dietmar Eggemann wrote: > On 6/12/19 9:32 PM, Rik van Riel wrote: > > Flatten the hierarchical runqueues into just the per CPU rq.cfs > > runqueue. > > > > Iteration of the sched_entity hierarchy is rate limited to once per > > jiffy > > per sched_entity, which is a smaller change than it seems, because > > load > > average adjustments were already rate limited to once per jiffy > > before this > > patch series. > > > > This patch breaks CONFIG_CFS_BANDWIDTH. The plan for that is to > > park tasks > > from throttled cgroups onto their cgroup runqueues, and slowly > > (using the > > GENTLE_FAIR_SLEEPERS) wake them back up, in vruntime order, once > > the cgroup > > gets unthrottled, to prevent thundering herd issues. > > > > Signed-off-by: Rik van Riel <riel@surriel.com> > > --- > > include/linux/sched.h | 2 + > > kernel/sched/fair.c | 478 +++++++++++++++++--------------------- > > ---- > > kernel/sched/pelt.c | 6 +- > > kernel/sched/pelt.h | 2 +- > > kernel/sched/sched.h | 2 +- > > 5 files changed, 194 insertions(+), 296 deletions(-) > > > > [...] > > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > > [...] > > > @@ -3491,7 +3544,7 @@ static inline bool update_load_avg(struct > > cfs_rq *cfs_rq, struct sched_entity *s > > * track group sched_entity load average for task_h_load calc > > in migration > > */ > > if (se->avg.last_update_time && !(flags & SKIP_AGE_LOAD)) > > - updated = __update_load_avg_se(now, cfs_rq, se); > > + updated = __update_load_avg_se(now, cfs_rq, se, curr, > > curr); > > I wonder if task migration is still working correctly. > > migrate_task_rq_fair(p, ...) -> remove_entity_load_avg(&p->se) would > use > cfs_rq = se->cfs_rq (i.e. root cfs_rq). So load (and util) will not > propagate through the taskgroup hierarchy. > > [...]
Good point. This should be the group cfs_rq, and then on the next tick the load change will be propagated up.
Let me add that change in for v2 as well.
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