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Date: Wed, 1 Apr 2015 11:22:41 +0800
Message-ID: <CADcy93X8hzw6xt9zD6YC6xDc4nUPfQhFz=G-FW5Ykf0LyjnDjw@mail.gmail.com>
Subject: Re: [PATCH v10 07/11] sched: get CPU's usage statistic
From: Xunlei Pang <pang.xunlei@linaro.org>
To: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@kernel.org>,
        lkml <linux-kernel@vger.kernel.org>,
        Preeti U Murthy <preeti@linux.vnet.ibm.com>,
        Morten Rasmussen <Morten.Rasmussen@arm.com>,
        Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>,
        Rik van Riel <riel@redhat.com>,
        Linaro Kernel Mailman List <linaro-kernel@lists.linaro.org>,
        Mike Galbraith <efault@gmx.de>,
        Dietmar Eggemann <dietmar.eggemann@arm.com>
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Vincent,
On 27 March 2015 at 23:37, Vincent Guittot <vincent.guittot@linaro.org> wrote:
> On 27 March 2015 at 16:12, Xunlei Pang <pang.xunlei@linaro.org> wrote:
>>> +static int get_cpu_usage(int cpu)
>>> +{
>>> +       unsigned long usage = cpu_rq(cpu)->cfs.utilization_load_avg;
>>> +       unsigned long capacity = capacity_orig_of(cpu);
>>> +
>>> +       if (usage >= SCHED_LOAD_SCALE)
>>> +               return capacity;
>>
>> Can "capacity" be greater than SCHED_LOAD_SCALE?
>> Why use SCHED_LOAD_SCALE instead of "capacity" in this judgement?
>
> Yes, SCHED_LOAD_SCALE is the default value but the capacity can be in
> the range [1536:512] for arm as an example

Right, I was confused between cpu capacity and
arch_scale_freq_capacity() in "Patch 04"  then. Thanks.

-Xunlei