Messages in this thread | | | From | Joel Fernandes <> | Date | Tue, 4 Jul 2023 13:25:49 -0400 | Subject | Re: [RFC PATCH V3 4/6] sched/deadline: Introduce deadline servers |
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On Tue, Jul 4, 2023 at 11:52 AM Daniel Bristot de Oliveira <bristot@redhat.com> wrote: > > > Back from EOSS... > > On 6/23/23 18:47, Valentin Schneider wrote: > > On 08/06/23 17:58, Daniel Bristot de Oliveira wrote: > >> @@ -2033,9 +2147,20 @@ static struct task_struct *pick_next_task_dl(struct rq *rq) > >> struct task_struct *p; > >> > >> p = pick_task_dl(rq); > >> - if (p) > >> + if (!p) > >> + return p; > >> + > >> + /* > >> + * XXX: re-check !dl_server, changed from v2 because of > >> + * pick_next_task_dl change > >> + */ > >> + if (!dl_server(&p->dl)) > >> set_next_task_dl(rq, p, true); > >> > > > > Should this be > > > > if (!p->server) > > > > instead? AFAICT dl_server(&p->dl) can never be true since there's no > > pi_se-like link to the server via the dl_se, only via the task_struct, and > > the server pick cannot return the server itself (as it's a pure sched_entity). > > makes sense... I will check that in the v4.
Makes sense to me too. Since p is either a real DL task or a CFS task, "if (dl_server(&p->dl))" is incorrect. "if (p->server)" is the right check.
Optionally, a BUG_ON() as well could be added to make sure the p returned by pick_task_dl() is always false: BUG_ON(dl_server(&p->dl));
thanks,
- Joel
> > > > >> + /* XXX not quite right */ > >> + if (hrtick_enabled(rq)) > >> + start_hrtick_dl(rq, &p->dl); > >> + > > > > IIUC that got hauled out of set_next_task_dl() to cover the case where we > > pick the server (+ the server pick) and want to more thoroughly enforce the > > server's bandwidth. If so, what's the issue with starting the hrtick here? > > I think that the commend was added more as a check if it is correct... it seems it is. > > Thanks Vale! > -- Daniel > > > > >> return p; > >> } > >> > > >
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