From: Juri Lelli <juri.lelli@redhat.com>
To: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
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: Thu, 8 Aug 2019 08:52:25 +0200 [thread overview]
Message-ID: <20190808065225.GD29310@localhost.localdomain> (raw)
In-Reply-To: <34710762-f813-3913-0e55-fde7c91c6c2d@arm.com>
Hi Dietmar,
On 07/08/19 18:31, 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.
>
> ...
> [ 0.530216] root domain span: 0-5 (max cpu_capacity = 1024)
> [ 0.538655] devtmpfs: initialized
> [ 0.556485] update_curr: rq mismatch rq[0] != rq[4]
> [ 0.561519] update_curr: rq mismatch rq[0] != rq[4]
> [ 0.566497] update_curr: rq mismatch rq[0] != rq[4]
> [ 0.571443] update_curr: rq mismatch rq[0] != rq[4]
> [ 0.576762] update_curr: rq mismatch rq[2] != rq[4]
> [ 0.581674] update_curr: rq mismatch rq[2] != rq[4]
> [ 0.586569] ------------[ cut here ]------------
> [ 0.591220] WARNING: CPU: 2 PID: 2 at kernel/sched/deadline.c:916 start_dl_timer+0x160/0x178
> [ 0.599686] Modules linked in:
> [ 0.602756] CPU: 2 PID: 2 Comm: kthreadd Tainted: G W 5.3.0-rc3-00013-ga33cf033cc99-dirty #64
> [ 0.612620] Hardware name: ARM Juno development board (r0) (DT)
> [ 0.618560] pstate: 60000085 (nZCv daIf -PAN -UAO)
> [ 0.623369] pc : start_dl_timer+0x160/0x178
> [ 0.627572] lr : start_dl_timer+0x160/0x178
> [ 0.631768] sp : ffff000010013cb0
> ...
> [ 0.715075] Call trace:
> [ 0.717531] start_dl_timer+0x160/0x178
> [ 0.721382] update_curr_dl_se+0x108/0x208
> [ 0.725494] dl_server_update+0x2c/0x38
> [ 0.729348] update_curr+0x1b4/0x3b8
> [ 0.732934] task_tick_fair+0x74/0xa88
> [ 0.736698] scheduler_tick+0x94/0x110
> [ 0.740461] update_process_times+0x48/0x60
> ...
>
> Seems to be related to the fact that the rq can change:
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index e4c14851a34c..5e3130a200ec 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -891,8 +891,17 @@ static void update_curr(struct cfs_rq *cfs_rq)
> 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)
> + if (curtask->server) {
> + struct rq *rq = rq_of(cfs_rq);
> + struct rq *rq2 = curtask->server->rq;
> +
> + if (rq != rq2) {
> + printk("update_curr: rq mismatch rq[%d] != rq[%d]\n",
> + cpu_of(rq), cpu_of(rq2));
> + }
> +
> dl_server_update(curtask->server, delta_exec);
> + }
> }
>
> ...
Yeah, I actually noticed the same. Some debugging seems to point to
early boot spawning of kthreads. I can reliably for example attribute
this mismatch to ksoftirqd(s). It looks like they can avoid the
dl_server assignment in pick_next_task_dl() and this breaks things.
Still need to figure out why this happens and how to fix it, though.
Best,
Juri
next prev parent reply other threads:[~2019-08-08 6:52 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 [this message]
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
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
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