From: Joel Fernandes <joel@joelfernandes.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 v2 01/12] sched/core: uclamp: extend sched_setattr to support utilization clamping
Date: Tue, 17 Jul 2018 11:04:34 -0700 [thread overview]
Message-ID: <20180717180434.GB150378@joelaf.mtv.corp.google.com> (raw)
In-Reply-To: <20180716082906.6061-2-patrick.bellasi@arm.com>
On Mon, Jul 16, 2018 at 09:28:55AM +0100, Patrick Bellasi wrote:
> The SCHED_DEADLINE scheduling class provides an advanced and formal
> model to define tasks requirements which can be translated into proper
> decisions for both task placements and frequencies selections.
> Other classes have a more simplified model which is essentially based on
> the relatively simple concept of POSIX priorities.
>
> Such a simple priority based model however does not allow to exploit
> some of the most advanced features of the Linux scheduler like, for
> example, driving frequencies selection via the schedutil cpufreq
> governor. However, also for non SCHED_DEADLINE tasks, it's still
> interesting to define tasks properties which can be used to better
> support certain scheduler decisions.
>
> Utilization clamping aims at exposing to user-space a new set of
> per-task attributes which can be used to provide the scheduler with some
> hints about the expected/required utilization for a task.
> This will allow to implement a more advanced per-task frequency control
> mechanism which is not based just on a "passive" measured task
> utilization but on a more "active" approach. For example, it could be
> possible to boost interactive tasks, thus getting better performance, or
> cap background tasks, thus being more energy efficient.
> Ultimately, such a mechanism can be considered similar to the cpufreq's
> powersave, performance and userspace governor but with a much fine
> grained and per-task control.
>
> Let's introduce a new API to set utilization clamping values for a
> specified task by extending sched_setattr, a syscall which already
> allows to define task specific properties for different scheduling
> classes.
> Specifically, a new pair of attributes allows to specify a minimum and
> maximum utilization which the scheduler should consider for a task.
>
> 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: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> Cc: Vincent Guittot <vincent.guittot@linaro.org>
> Cc: Viresh Kumar <viresh.kumar@linaro.org>
> Cc: Paul Turner <pjt@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
> ---
> include/linux/sched.h | 16 ++++++++
> include/uapi/linux/sched.h | 4 +-
> include/uapi/linux/sched/types.h | 64 +++++++++++++++++++++++++++-----
> init/Kconfig | 19 ++++++++++
> kernel/sched/core.c | 39 +++++++++++++++++++
> 5 files changed, 132 insertions(+), 10 deletions(-)
>
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index 43731fe51c97..fd8495723088 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -279,6 +279,17 @@ struct vtime {
> u64 gtime;
> };
>
> +enum uclamp_id {
> + /* No utilization clamp group assigned */
> + UCLAMP_NONE = -1,
> +
> + UCLAMP_MIN = 0, /* Minimum utilization */
> + UCLAMP_MAX, /* Maximum utilization */
> +
> + /* Utilization clamping constraints count */
> + UCLAMP_CNT
> +};
> +
> struct sched_info {
> #ifdef CONFIG_SCHED_INFO
> /* Cumulative counters: */
> @@ -649,6 +660,11 @@ struct task_struct {
> #endif
> struct sched_dl_entity dl;
>
> +#ifdef CONFIG_UCLAMP_TASK
> + /* Utlization clamp values for this task */
> + int uclamp[UCLAMP_CNT];
> +#endif
Seems a bit wasteful to me. Seems you need 2 values that are in the range
0..1024. Can we not do better with task_struct space usage?
thanks!
- Joel
next prev parent reply other threads:[~2018-07-17 18:04 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-16 8:28 [PATCH v2 00/12] Add utilization clamping support Patrick Bellasi
2018-07-16 8:28 ` [PATCH v2 01/12] sched/core: uclamp: extend sched_setattr to support utilization clamping Patrick Bellasi
2018-07-17 17:50 ` Joel Fernandes
2018-07-18 8:42 ` Patrick Bellasi
2018-07-18 17:02 ` Joel Fernandes
2018-07-17 18:04 ` Joel Fernandes [this message]
2018-07-16 8:28 ` [PATCH v2 02/12] sched/core: uclamp: map TASK's clamp values into CPU's clamp groups Patrick Bellasi
2018-07-19 23:51 ` Suren Baghdasaryan
2018-07-20 15:11 ` Patrick Bellasi
2018-07-21 0:25 ` Suren Baghdasaryan
2018-07-23 13:36 ` Patrick Bellasi
2018-07-16 8:28 ` [PATCH v2 03/12] sched/core: uclamp: add CPU's clamp groups accounting Patrick Bellasi
2018-07-20 20:25 ` Suren Baghdasaryan
2018-07-16 8:28 ` [PATCH v2 04/12] sched/core: uclamp: update CPU's refcount on clamp changes Patrick Bellasi
2018-07-16 8:28 ` [PATCH v2 05/12] sched/cpufreq: uclamp: add utilization clamping for FAIR tasks Patrick Bellasi
2018-07-16 8:29 ` [PATCH v2 06/12] sched/cpufreq: uclamp: add utilization clamping for RT tasks Patrick Bellasi
2018-07-16 8:29 ` [PATCH v2 07/12] sched/core: uclamp: enforce last task UCLAMP_MAX Patrick Bellasi
2018-07-21 1:23 ` Suren Baghdasaryan
2018-07-23 15:02 ` Patrick Bellasi
2018-07-23 16:40 ` Suren Baghdasaryan
2018-07-16 8:29 ` [PATCH v2 08/12] sched/core: uclamp: extend cpu's cgroup controller Patrick Bellasi
2018-07-21 2:37 ` Suren Baghdasaryan
2018-07-21 3:16 ` Suren Baghdasaryan
2018-07-23 15:17 ` Patrick Bellasi
2018-07-23 15:30 ` Tejun Heo
2018-07-23 17:22 ` Patrick Bellasi
2018-07-24 13:29 ` Tejun Heo
2018-07-24 15:39 ` Patrick Bellasi
2018-07-27 0:39 ` Joel Fernandes
2018-07-27 8:09 ` Quentin Perret
2018-07-16 8:29 ` [PATCH v2 09/12] sched/core: uclamp: map TG's clamp values into CPU's clamp groups Patrick Bellasi
2018-07-16 8:29 ` [PATCH v2 10/12] sched/core: uclamp: use TG's clamps to restrict Task's clamps Patrick Bellasi
2018-07-22 3:05 ` Suren Baghdasaryan
2018-07-23 15:40 ` Patrick Bellasi
2018-07-23 17:11 ` Suren Baghdasaryan
2018-07-24 9:56 ` Patrick Bellasi
2018-07-24 15:28 ` Suren Baghdasaryan
2018-07-24 15:49 ` Patrick Bellasi
2018-07-16 8:29 ` [PATCH v2 11/12] sched/core: uclamp: update CPU's refcount on TG's clamp changes Patrick Bellasi
2018-07-22 3:17 ` Suren Baghdasaryan
2018-07-16 8:29 ` [PATCH v2 12/12] sched/core: uclamp: use percentage clamp values Patrick Bellasi
2018-07-22 4:04 ` Suren Baghdasaryan
2018-07-24 16:43 ` Patrick Bellasi
2018-07-24 17:11 ` Suren Baghdasaryan
2018-07-24 17:17 ` Patrick Bellasi
2018-07-17 13:03 ` [PATCH v2 00/12] Add utilization clamping support Joel Fernandes
2018-07-17 13:41 ` Patrick Bellasi
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