On 21/04/17 21:08, Luca Abeni wrote: > On Fri, 21 Apr 2017 11:26:59 +0100 > Juri Lelli <juri.le...@arm.com> wrote: > > On 21/04/17 11:59, Luca Abeni wrote: > > > On Fri, 21 Apr 2017 10:47:29 +0100 > > > Juri Lelli <juri.le...@arm.com> wrote: > > > [...] > > > > > > > *dl_se, update_dl_entity(dl_se, pi_se); > > > > > > > else if (flags & ENQUEUE_REPLENISH) > > > > > > > replenish_dl_entity(dl_se, pi_se); > > > > > > > + else if ((flags & ENQUEUE_RESTORE) && > > > > > > > > > > > > Not sure I understand how this works. AFAICT we are doing > > > > > > __sched_setscheduler() when we want to catch the case of a new > > > > > > dl_entity (SCHED_{OTHER,FIFO} -> SCHED_DEADLINE}, but > > > > > > queue_flags (which are passed to enqueue_task()) don't seem > > > > > > to have ENQUEUE_RESTORE set? > > > > > > > > > > I was under the impression sched_setscheduler() sets > > > > > ENQUEUE_RESTORE... > > > > > > > > Oh, I think it works "by coincidence", as ENQUEUE_RESTORE == > > > > DEQUEUE_SAVE == 0x02 ? :) > > > > > > Not sure if this is a conincidence... By looking at the comments in > > > sched/sched.h I got the impression the two values match by design > > > (and __sched_setscheduler() is using this property to simplify the > > > code :) > > > > Yep, right. > > > > Do you think we might get into trouble with do_set_cpus_allowed()? > > Can it happen that we change a task affinity while its deadline is in > > the past? > > Well, double thinking about it, this is an interesting problem... What > do we want to do with do_set_cpus_allowed()? (I mean: what is the > expected behaviour?) > > With this patch, if a task is moved to a different runqueue when its > deadline is in the past (because we are doing gEDF, or because of timer > granularity issues) its scheduling deadline is reinitialized to current > time + relative deadline... I think this makes perfect sense, doesn't > it? >
Mmm, I don't think we will (with this patch) actually reinitialize the deadline when a "normal" gEDF migration happen (push/pull), as (de)activate_task() have no flag set. Which brings the question, should we actually take care of this corner case (as what you say makes sense to me too)?