From: Dietmar Eggemann <dietmar.eggemann@arm.com>
To: Patrick Bellasi <patrick.bellasi@arm.com>,
linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org
Cc: Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>, Tejun Heo <tj@kernel.org>,
"Rafael J . Wysocki" <rafael.j.wysocki@intel.com>,
Viresh Kumar <viresh.kumar@linaro.org>,
Vincent Guittot <vincent.guittot@linaro.org>,
Paul Turner <pjt@google.com>,
Morten Rasmussen <morten.rasmussen@arm.com>,
Juri Lelli <juri.lelli@redhat.com>, Todd Kjos <tkjos@google.com>,
Joel Fernandes <joelaf@google.com>,
Steve Muckle <smuckle@google.com>,
Suren Baghdasaryan <surenb@google.com>
Subject: Re: [PATCH v3 03/14] sched/core: uclamp: add CPU's clamp groups accounting
Date: Tue, 14 Aug 2018 17:44:15 +0200 [thread overview]
Message-ID: <a24def9b-57bb-d072-5064-0421076d2e43@arm.com> (raw)
In-Reply-To: <20180806163946.28380-4-patrick.bellasi@arm.com>
On 08/06/2018 06:39 PM, Patrick Bellasi wrote:
[...]
> +/**
> + * uclamp_cpu_put_id(): decrease reference count for a clamp group on a CPU
> + * @p: the task being dequeued from a CPU
> + * @cpu: the CPU from where the clamp group has to be released
> + * @clamp_id: the utilization clamp (e.g. min or max utilization) to release
> + *
> + * When a task is dequeued from a CPU's RQ, the CPU's clamp group reference
> + * counted by the task is decreased.
> + * If this was the last task defining the current max clamp group, then the
> + * CPU clamping is updated to find the new max for the specified clamp
> + * index.
> + */
> +static inline void uclamp_cpu_put_id(struct task_struct *p,
> + struct rq *rq, int clamp_id)
> +{
> + struct uclamp_group *uc_grp;
> + struct uclamp_cpu *uc_cpu;
> + unsigned int clamp_value;
> + int group_id;
> +
> + /* No task specific clamp values: nothing to do */
> + group_id = p->uclamp[clamp_id].group_id;
> + if (group_id == UCLAMP_NOT_VALID)
> + return;
> +
> + /* Decrement the task's reference counted group index */
> + uc_grp = &rq->uclamp.group[clamp_id][0];
> +#ifdef SCHED_DEBUG
> + if (unlikely(uc_grp[group_id].tasks == 0)) {
> + WARN(1, "invalid CPU[%d] clamp group [%d:%d] refcount\n",
> + cpu_of(rq), clamp_id, group_id);
> + uc_grp[group_id].tasks = 1;
> + }
> +#endif
This one indicates that there are some holes in your ref-counting. It's
probably easier to debug that there is still a task but the
uc_grp[group_id].tasks value == 0 (A). I assume the other problem exists
as well, i.e. last task and uc_grp[group_id].tasks > 1 (B)?
You have uclamp_cpu_[get/put](_id)() in [enqueue/dequeue]_task.
Patch 04/14 introduces its use in uclamp_task_update_active().
Do you know why (A) (and (B)) are happening?
> + uc_grp[group_id].tasks -= 1;
> +
> + /* If this is not the last task, no updates are required */
> + if (uc_grp[group_id].tasks > 0)
> + return;
> +
> + /*
> + * Update the CPU only if this was the last task of the group
> + * defining the current clamp value.
> + */
> + uc_cpu = &rq->uclamp;
> + clamp_value = uc_grp[group_id].value;
> + if (clamp_value >= uc_cpu->value[clamp_id])
'clamp_value > uc_cpu->value[clamp_id]' should indicate another
inconsistency in the uclamp machinery, right?
[...]
next prev parent reply other threads:[~2018-08-14 15:44 UTC|newest]
Thread overview: 82+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-06 16:39 [PATCH v3 00/14] Add utilization clamping support Patrick Bellasi
2018-08-06 16:39 ` [PATCH v3 01/14] sched/core: uclamp: extend sched_setattr to support utilization clamping Patrick Bellasi
2018-08-06 16:50 ` Randy Dunlap
2018-08-09 8:39 ` Patrick Bellasi
2018-08-09 15:20 ` Randy Dunlap
2018-08-07 9:59 ` Juri Lelli
2018-08-13 12:14 ` Patrick Bellasi
2018-08-13 12:27 ` Juri Lelli
2018-08-07 12:35 ` Juri Lelli
2018-08-09 9:14 ` Patrick Bellasi
2018-08-09 9:50 ` Juri Lelli
2018-08-09 15:23 ` Patrick Bellasi
2018-08-10 7:50 ` Juri Lelli
2018-08-17 10:34 ` Quentin Perret
2018-08-17 10:57 ` Patrick Bellasi
2018-08-17 11:14 ` Quentin Perret
2018-08-06 16:39 ` [PATCH v3 02/14] sched/core: uclamp: map TASK's clamp values into CPU's clamp groups Patrick Bellasi
2018-08-14 11:25 ` Pavan Kondeti
2018-08-14 15:21 ` Patrick Bellasi
2018-08-06 16:39 ` [PATCH v3 03/14] sched/core: uclamp: add CPU's clamp groups accounting Patrick Bellasi
2018-08-14 15:44 ` Dietmar Eggemann [this message]
2018-08-14 16:49 ` Patrick Bellasi
2018-08-15 9:37 ` Dietmar Eggemann
2018-08-15 10:54 ` Patrick Bellasi
2018-08-15 10:59 ` Dietmar Eggemann
2018-08-16 13:32 ` Patrick Bellasi
2018-08-16 13:37 ` Quentin Perret
2018-08-16 13:45 ` Dietmar Eggemann
2018-08-16 14:21 ` Quentin Perret
2018-08-16 15:00 ` Dietmar Eggemann
2018-08-17 11:04 ` Patrick Bellasi
2018-08-06 16:39 ` [PATCH v3 04/14] sched/core: uclamp: update CPU's refcount on clamp changes Patrick Bellasi
2018-08-15 15:02 ` Dietmar Eggemann
2018-08-16 13:22 ` Patrick Bellasi
2018-08-06 16:39 ` [PATCH v3 05/14] sched/cpufreq: uclamp: add utilization clamping for FAIR tasks Patrick Bellasi
2018-08-08 13:18 ` Vincent Guittot
2018-08-09 15:30 ` Patrick Bellasi
2018-08-15 15:30 ` Dietmar Eggemann
2018-08-16 13:53 ` Patrick Bellasi
2018-08-06 16:39 ` [PATCH v3 06/14] sched/cpufreq: uclamp: add utilization clamping for RT tasks Patrick Bellasi
2018-08-07 13:26 ` Juri Lelli
2018-08-09 15:34 ` Patrick Bellasi
2018-08-09 16:03 ` Vincent Guittot
2018-08-13 10:12 ` Patrick Bellasi
2018-08-13 10:50 ` Juri Lelli
2018-08-13 12:07 ` Vincent Guittot
2018-08-13 12:09 ` Vincent Guittot
2018-08-13 12:49 ` Patrick Bellasi
2018-08-13 14:06 ` Vincent Guittot
2018-08-13 15:01 ` Patrick Bellasi
2018-08-16 10:34 ` Dietmar Eggemann
2018-08-16 13:40 ` Patrick Bellasi
2018-08-07 13:54 ` Quentin Perret
2018-08-09 15:41 ` Patrick Bellasi
2018-08-09 15:55 ` Quentin Perret
2018-08-13 10:17 ` Patrick Bellasi
2018-08-06 16:39 ` [PATCH v3 07/14] sched/core: uclamp: enforce last task UCLAMP_MAX Patrick Bellasi
2018-08-16 15:43 ` Dietmar Eggemann
2018-08-16 16:47 ` Patrick Bellasi
2018-08-16 17:10 ` Dietmar Eggemann
2018-08-16 17:27 ` Patrick Bellasi
2018-08-16 17:20 ` Patrick Bellasi
2018-08-06 16:39 ` [PATCH v3 08/14] sched/core: uclamp: extend cpu's cgroup controller Patrick Bellasi
2018-08-17 12:21 ` Dietmar Eggemann
2018-08-17 14:24 ` Patrick Bellasi
2018-08-06 16:39 ` [PATCH v3 09/14] sched/core: uclamp: propagate parent clamps Patrick Bellasi
2018-08-16 9:09 ` Pavan Kondeti
2018-08-16 14:07 ` Patrick Bellasi
2018-08-17 13:43 ` Dietmar Eggemann
2018-08-17 14:45 ` Patrick Bellasi
2018-08-17 15:50 ` Dietmar Eggemann
2018-08-20 10:01 ` Dietmar Eggemann
2018-08-20 12:28 ` Patrick Bellasi
2018-08-06 16:39 ` [PATCH v3 10/14] sched/core: uclamp: map TG's clamp values into CPU's clamp groups Patrick Bellasi
2018-08-06 16:39 ` [PATCH v3 11/14] sched/core: uclamp: use TG's clamps to restrict Task's clamps Patrick Bellasi
2018-08-06 16:39 ` [PATCH v3 12/14] sched/core: uclamp: add system default clamps Patrick Bellasi
2018-08-16 9:13 ` Pavan Kondeti
2018-08-16 14:37 ` Patrick Bellasi
2018-08-20 10:18 ` Dietmar Eggemann
2018-08-20 12:27 ` Patrick Bellasi
2018-08-06 16:39 ` [PATCH v3 13/14] sched/core: uclamp: update CPU's refcount on TG's clamp changes Patrick Bellasi
2018-08-06 16:39 ` [PATCH v3 14/14] sched/core: uclamp: use percentage clamp values Patrick Bellasi
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