Messages in this thread | | | Date | Thu, 8 Aug 2019 11:27:44 +0200 | From | Juri Lelli <> | Subject | Re: [RFC][PATCH 12/13] sched/deadline: Introduce deadline servers |
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On 08/08/19 10:57, Dietmar Eggemann wrote: > On 8/8/19 10:46 AM, Juri Lelli wrote: > > On 08/08/19 10:11, Dietmar Eggemann wrote: > >> On 8/8/19 9:56 AM, Peter Zijlstra wrote: > >>> On Wed, Aug 07, 2019 at 06:31:59PM +0200, Dietmar Eggemann wrote: > >>>> On 7/26/19 4:54 PM, Peter Zijlstra wrote: > >>>>> > >>>>> > >>>>> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> > >>>> > >>>> [...] > >>>> > >>>>> @@ -889,6 +891,8 @@ static void update_curr(struct cfs_rq *c > >>>>> trace_sched_stat_runtime(curtask, delta_exec, curr->vruntime); > >>>>> cgroup_account_cputime(curtask, delta_exec); > >>>>> account_group_exec_runtime(curtask, delta_exec); > >>>>> + if (curtask->server) > >>>>> + dl_server_update(curtask->server, delta_exec); > >>>>> } > >>>> > >>>> I get a lockdep_assert_held(&rq->lock) related warning in start_dl_timer() > >>>> when running the full stack. > >>> > >>> That would seem to imply a stale curtask->server value; the hunk below: > >>> > >>> --- a/kernel/sched/core.c > >>> +++ b/kernel/sched/core.c > >>> @@ -3756,8 +3756,11 @@ pick_next_task(struct rq *rq, struct tas > >>> > >>> for_each_class(class) { > >>> p = class->pick_next_task(rq, NULL, NULL); > >>> - if (p) > >>> + if (p) { > >>> + if (p->sched_class == class && p->server) > >>> + p->server = NULL; > >>> return p; > >>> + } > >>> } > >>> > >>> > >>> Was supposed to clear p->server, but clearly something is going 'funny'. > >> > >> What about the fast path in pick_next_task()? > >> > >> diff --git a/kernel/sched/core.c b/kernel/sched/core.c > >> index bffe849b5a42..f1ea6ae16052 100644 > >> --- a/kernel/sched/core.c > >> +++ b/kernel/sched/core.c > >> @@ -3742,6 +3742,9 @@ pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) > >> if (unlikely(!p)) > >> p = idle_sched_class.pick_next_task(rq, prev, rf); > >> > >> + if (p->sched_class == &fair_sched_class && p->server) > >> + p->server = NULL; > >> + > > > > Hummm, but then who sets it back to the correct server. AFAIU > > update_curr() needs a ->server to do the correct DL accounting? > > Ah, OK, this would kill the whole functionality ;-) >
I'm thinking we could use &rq->fair_server. It seems to pass the point we are discussing about, but then virt box becomes unresponsive (busy loops).
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