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) <[email protected]> > >> > >> [...] > >> > >>> @@ -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?
