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From:   "Rafael J. Wysocki" <rjw@rjwysocki.net>
To:     Quentin Perret <quentin.perret@arm.com>
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Subject: Re: [PATCH v6 10/14] sched/cpufreq: Refactor the utilization aggregation method
Date:   Mon, 10 Sep 2018 11:53:58 +0200
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In-Reply-To: <20180820094420.26590-11-quentin.perret@arm.com>
References: <20180820094420.26590-1-quentin.perret@arm.com> <20180820094420.26590-11-quentin.perret@arm.com>
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On Monday, August 20, 2018 11:44:16 AM CEST Quentin Perret wrote:
> Schedutil aggregates the PELT signals of CFS, RT, DL and IRQ in order
> to decide which frequency to request. Energy Aware Scheduling (EAS)
> needs to be able to predict those requests to assess the energy impact
> of scheduling decisions. However, the PELT signals aggregation is only
> done in schedutil for now, hence making it hard to synchronize it with
> EAS.
> 
> To address this issue, introduce schedutil_freq_util() to perform the
> aforementioned aggregation and make it available to other parts of the
> scheduler. Since frequency selection and energy estimation still need
> to deal with RT and DL signals slightly differently, schedutil_freq_util()
> is called with a different 'type' parameter in those two contexts, and
> returns an aggregated utilization signal accordingly.

This is complementary to patch [02/14] IMO.

schedutil_freq_util() and map_util_freq() introduced by that patch should
always be used together as they are two parts of one algorithm in my view.

Would it be possible to make that clearer?

Thanks,
Rafael