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Date:   Wed, 12 Sep 2018 19:34:21 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Patrick Bellasi <patrick.bellasi@arm.com>
Cc:     linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org,
        Ingo Molnar <mingo@redhat.com>, 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>,
        Quentin Perret <quentin.perret@arm.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 v4 03/16] sched/core: uclamp: add CPU's clamp groups
 accounting
Message-ID: <20180912173421.GX24082@hirez.programming.kicks-ass.net>
References: <20180828135324.21976-1-patrick.bellasi@arm.com>
 <20180828135324.21976-4-patrick.bellasi@arm.com>
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On Tue, Aug 28, 2018 at 02:53:11PM +0100, Patrick Bellasi wrote:
> diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
> index 72df2dc779bc..513608ae4908 100644
> --- a/kernel/sched/sched.h
> +++ b/kernel/sched/sched.h
> @@ -764,6 +764,50 @@ extern void rto_push_irq_work_func(struct irq_work *work);
>  #endif
>  #endif /* CONFIG_SMP */
>  
> +#ifdef CONFIG_UCLAMP_TASK
> +/**
> + * struct uclamp_group - Utilization clamp Group
> + * @value: utilization clamp value for tasks on this clamp group
> + * @tasks: number of RUNNABLE tasks on this clamp group
> + *
> + * Keep track of how many tasks are RUNNABLE for a given utilization
> + * clamp value.
> + */
> +struct uclamp_group {
> +	int value;
> +	int tasks;
> +};

We could use bit fields again to compress in 10:22 bits I suppose. 4M
tasks is quite a lot to have runnable on a single CPU ;-)