From: Juri Lelli <juri.lelli@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>,
mingo@kernel.org, linux-kernel@vger.kernel.org,
luca.abeni@santannapisa.it, bristot@redhat.com,
balsini@android.com, dvyukov@google.com, tglx@linutronix.de,
vpillai@digitalocean.com, rostedt@goodmis.org
Subject: Re: [RFC][PATCH 12/13] sched/deadline: Introduce deadline servers
Date: Fri, 9 Aug 2019 09:13:06 +0200 [thread overview]
Message-ID: <20190809071306.GL29310@localhost.localdomain> (raw)
In-Reply-To: <20190808103109.GF2369@hirez.programming.kicks-ass.net>
On 08/08/19 12:31, Peter Zijlstra wrote:
> On Thu, Aug 08, 2019 at 10:46:52AM +0200, Juri Lelli wrote:
> > On 08/08/19 10:11, Dietmar Eggemann wrote:
>
> > > 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?
>
> The above looks ok.
>
> The pick_next_task_dl() when it selects a server will set ->server.
OK. Yesterday's IRC conversation resolved my perplexity about this
point. I tried to summarize what I've got in the comment below (which we
might want to add on top of Dietmar's fix).
--->8---
/*
* Since we are executing the fast path it means that the DL
* server was throttled and we'll now be scheduled w/o it. So,
* reset p's pointer to it (accounting won't be performed, as
* it wouldn't make sense while server is thottled).
*/
next prev parent reply other threads:[~2019-08-09 7:13 UTC|newest]
Thread overview: 63+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-26 14:54 [RFC][PATCH 00/13] SCHED_DEADLINE server infrastructure Peter Zijlstra
2019-07-26 14:54 ` [RFC][PATCH 01/13] sched/deadline: Impose global limits on sched_attr::sched_period Peter Zijlstra
2019-07-29 8:57 ` Juri Lelli
2019-07-29 11:45 ` Daniel Bristot de Oliveira
2019-08-02 17:21 ` Alessio Balsini
2019-08-05 11:53 ` Peter Zijlstra
2019-08-22 12:29 ` Alessio Balsini
2019-08-22 16:51 ` Peter Zijlstra
2019-08-31 14:41 ` Alessio Balsini
2019-09-02 9:16 ` Peter Zijlstra
2019-09-02 12:31 ` Peter Zijlstra
2019-09-04 10:16 ` Steven Rostedt
2019-09-04 11:30 ` Peter Zijlstra
2019-09-04 13:24 ` Joel Fernandes
2019-09-04 14:11 ` Will Deacon
2019-09-04 14:35 ` Joel Fernandes
2019-09-04 15:52 ` Peter Zijlstra
2019-10-23 17:17 ` [PATCH 4.4 4.9 4.14] loop: Add LOOP_SET_DIRECT_IO to compat ioctl Alessio Balsini
2019-10-23 17:22 ` Alessio Balsini
2019-10-25 0:17 ` Sasha Levin
2020-05-20 18:38 ` [RFC][PATCH 01/13] sched/deadline: Impose global limits on sched_attr::sched_period Juri Lelli
2020-05-21 13:45 ` Daniel Bristot de Oliveira
2020-06-16 12:21 ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2019-07-26 14:54 ` [RFC][PATCH 02/13] stop_machine: Fix stop_cpus_in_progress ordering Peter Zijlstra
2019-07-30 13:16 ` Phil Auld
2019-07-30 13:22 ` Steven Rostedt
2019-07-26 14:54 ` [RFC][PATCH 03/13] sched: Fix kerneldoc comment for ia64_set_curr_task Peter Zijlstra
2019-07-26 14:54 ` [RFC][PATCH 04/13] sched/{rt,deadline}: Fix set_next_task vs pick_next_task Peter Zijlstra
2019-07-29 9:25 ` Juri Lelli
2019-07-29 11:15 ` Peter Zijlstra
2019-07-29 11:27 ` Juri Lelli
2019-07-29 13:04 ` Peter Zijlstra
2019-07-29 13:17 ` Juri Lelli
2019-07-29 14:40 ` Peter Zijlstra
2019-07-26 14:54 ` [RFC][PATCH 05/13] sched: Add task_struct pointer to sched_class::set_curr_task Peter Zijlstra
2019-07-26 14:54 ` [RFC][PATCH 06/13] sched/fair: Export newidle_balance() Peter Zijlstra
2019-07-26 14:54 ` [RFC][PATCH 07/13] sched: Allow put_prev_task() to drop rq->lock Peter Zijlstra
2019-07-26 14:54 ` [RFC][PATCH 08/13] sched: Rework pick_next_task() slow-path Peter Zijlstra
2019-07-26 14:54 ` [RFC][PATCH 09/13] sched: Unify runtime accounting across classes Peter Zijlstra
2019-07-26 14:54 ` [RFC][PATCH 10/13] sched/deadline: Collect sched_dl_entity initialization Peter Zijlstra
2019-07-26 14:54 ` [RFC][PATCH 11/13] sched/deadline: Move bandwidth accounting into {en,de}queue_dl_entity Peter Zijlstra
2019-07-26 14:54 ` [RFC][PATCH 12/13] sched/deadline: Introduce deadline servers Peter Zijlstra
2019-08-07 16:31 ` Dietmar Eggemann
2019-08-08 6:52 ` Juri Lelli
2019-08-08 7:52 ` Dietmar Eggemann
2019-08-08 7:56 ` Peter Zijlstra
2019-08-08 8:11 ` Dietmar Eggemann
2019-08-08 8:46 ` Juri Lelli
2019-08-08 8:57 ` Dietmar Eggemann
2019-08-08 9:27 ` Juri Lelli
2019-08-08 9:45 ` Juri Lelli
2019-08-30 11:24 ` Peter Zijlstra
2019-09-06 9:36 ` Juri Lelli
2019-08-08 10:31 ` Peter Zijlstra
2019-08-09 7:13 ` Juri Lelli [this message]
2019-08-08 6:59 ` Juri Lelli
2019-08-09 9:17 ` Dietmar Eggemann
2019-08-09 12:16 ` Juri Lelli
2019-07-26 14:54 ` [RFC][PATCH 13/13] sched/fair: Add trivial fair server Peter Zijlstra
2019-07-26 20:01 ` [RFC][PATCH 00/13] SCHED_DEADLINE server infrastructure luca abeni
2019-09-03 14:27 ` Alessio Balsini
2019-09-04 10:50 ` Juri Lelli
2019-09-04 11:32 ` Peter Zijlstra
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190809071306.GL29310@localhost.localdomain \
--to=juri.lelli@redhat.com \
--cc=balsini@android.com \
--cc=bristot@redhat.com \
--cc=dietmar.eggemann@arm.com \
--cc=dvyukov@google.com \
--cc=linux-kernel@vger.kernel.org \
--cc=luca.abeni@santannapisa.it \
--cc=mingo@kernel.org \
--cc=peterz@infradead.org \
--cc=rostedt@goodmis.org \
--cc=tglx@linutronix.de \
--cc=vpillai@digitalocean.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).