Messages in this thread | | | Subject | Re: [RFC][PATCH 12/13] sched/deadline: Introduce deadline servers | From | Dietmar Eggemann <> | Date | Thu, 8 Aug 2019 10:57:13 +0200 |
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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 ;-)
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