From: Pavan Kondeti <pkondeti@codeaurora.org>
To: Patrick Bellasi <patrick.bellasi@arm.com>
Cc: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org,
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>,
Dietmar Eggemann <dietmar.eggemann@arm.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 12/14] sched/core: uclamp: add system default clamps
Date: Thu, 16 Aug 2018 14:43:48 +0530 [thread overview]
Message-ID: <20180816091348.GD2661@codeaurora.org> (raw)
In-Reply-To: <20180806163946.28380-13-patrick.bellasi@arm.com>
On Mon, Aug 06, 2018 at 05:39:44PM +0100, Patrick Bellasi wrote:
> Clamp values cannot be tuned at the root cgroup level. Moreover, because
> of the delegation model requirements and how the parent clamps
> propagation works, if we want to enable subgroups to set a non null
> util.min, we need to be able to configure the root group util.min to the
> allow the maximum utilization (SCHED_CAPACITY_SCALE = 1024).
>
> Unfortunately this setup will also mean that all tasks running in the
> root group, will always get a maximum util.min clamp, unless they have a
> lower task specific clamp which is definitively not a desirable default
> configuration.
>
> Let's fix this by explicitly adding a system default configuration
> (sysctl_sched_uclamp_util_{min,max}) which works as a restrictive clamp
> for all tasks running on the root group.
>
> This interface is available independently from cgroups, thus providing a
> complete solution for system wide utilization clamping configuration.
>
> Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Tejun Heo <tj@kernel.org>
> Cc: Paul Turner <pjt@google.com>
> Cc: Suren Baghdasaryan <surenb@google.com>
> Cc: Todd Kjos <tkjos@google.com>
> Cc: Joel Fernandes <joelaf@google.com>
> Cc: Steve Muckle <smuckle@google.com>
> Cc: Juri Lelli <juri.lelli@redhat.com>
> Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
> Cc: Morten Rasmussen <morten.rasmussen@arm.com>
> Cc: linux-kernel@vger.kernel.org
> Cc: linux-pm@vger.kernel.org
<snip>
> +/*
> + * Minimum utilization for tasks in the root cgroup
> + * default: 0
> + */
> +unsigned int sysctl_sched_uclamp_util_min;
> +
> +/*
> + * Maximum utilization for tasks in the root cgroup
> + * default: 1024
> + */
> +unsigned int sysctl_sched_uclamp_util_max = 1024;
> +
> +static struct uclamp_se uclamp_default[UCLAMP_CNT];
> +
The default group id for un-clamped root tasks is 0 because of
this declaration, correct?
> /**
> * uclamp_map: reference counts a utilization "clamp value"
> * @value: the utilization "clamp value" required
> @@ -957,12 +971,25 @@ static inline int uclamp_task_group_id(struct task_struct *p, int clamp_id)
> group_id = uc_se->group_id;
>
> #ifdef CONFIG_UCLAMP_TASK_GROUP
> + /*
> + * Tasks in the root group, which do not have a task specific clamp
> + * value, get the system default calmp value.
> + */
> + if (group_id == UCLAMP_NOT_VALID &&
> + task_group(p) == &root_task_group) {
> + return uclamp_default[clamp_id].group_id;
> + }
> +
> /* Use TG's clamp value to limit task specific values */
> uc_se = &task_group(p)->uclamp[clamp_id];
> if (group_id == UCLAMP_NOT_VALID ||
> clamp_value > uc_se->effective.value) {
> group_id = uc_se->effective.group_id;
> }
> +#else
> + /* By default, all tasks get the system default clamp value */
> + if (group_id == UCLAMP_NOT_VALID)
> + return uclamp_default[clamp_id].group_id;
> #endif
>
> return group_id;
> @@ -1269,6 +1296,75 @@ static inline void uclamp_group_get(struct task_struct *p,
> uclamp_group_put(clamp_id, prev_group_id);
> }
>
> +int sched_uclamp_handler(struct ctl_table *table, int write,
> + void __user *buffer, size_t *lenp,
> + loff_t *ppos)
> +{
> + int group_id[UCLAMP_CNT] = { UCLAMP_NOT_VALID };
> + struct uclamp_se *uc_se;
> + int old_min, old_max;
> + int result;
> +
> + mutex_lock(&uclamp_mutex);
> +
> + old_min = sysctl_sched_uclamp_util_min;
> + old_max = sysctl_sched_uclamp_util_max;
> +
> + result = proc_dointvec(table, write, buffer, lenp, ppos);
> + if (result)
> + goto undo;
> + if (!write)
> + goto done;
> +
> + if (sysctl_sched_uclamp_util_min > sysctl_sched_uclamp_util_max)
> + goto undo;
> + if (sysctl_sched_uclamp_util_max > 1024)
> + goto undo;
> +
> + /* Find a valid group_id for each required clamp value */
> + if (old_min != sysctl_sched_uclamp_util_min) {
> + result = uclamp_group_find(UCLAMP_MIN, sysctl_sched_uclamp_util_min);
> + if (result == -ENOSPC) {
> + pr_err("Cannot allocate more than %d UTIL_MIN clamp groups\n",
> + CONFIG_UCLAMP_GROUPS_COUNT);
> + goto undo;
> + }
> + group_id[UCLAMP_MIN] = result;
> + }
> + if (old_max != sysctl_sched_uclamp_util_max) {
> + result = uclamp_group_find(UCLAMP_MAX, sysctl_sched_uclamp_util_max);
> + if (result == -ENOSPC) {
> + pr_err("Cannot allocate more than %d UTIL_MAX clamp groups\n",
> + CONFIG_UCLAMP_GROUPS_COUNT);
> + goto undo;
> + }
> + group_id[UCLAMP_MAX] = result;
> + }
> +
> + /* Update each required clamp group */
> + if (old_min != sysctl_sched_uclamp_util_min) {
> + uc_se = &uclamp_default[UCLAMP_MIN];
> + uclamp_group_get(NULL, UCLAMP_MIN, group_id[UCLAMP_MIN],
> + uc_se, sysctl_sched_uclamp_util_min);
> + }
> + if (old_max != sysctl_sched_uclamp_util_max) {
> + uc_se = &uclamp_default[UCLAMP_MAX];
> + uclamp_group_get(NULL, UCLAMP_MAX, group_id[UCLAMP_MAX],
> + uc_se, sysctl_sched_uclamp_util_max);
> + }
uclamp_group_get() also drops the reference on the previous group id.
The initial group id for uclamp_default[] i.e 0 is never claimed by
us. so we end up releasing it. But root group still points to group#0.
is this a problem?
--
Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project.
next prev parent reply other threads:[~2018-08-16 9:14 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
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 [this message]
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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