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From: Lukasz Luba <lukasz.luba@arm.com>
To: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Vincent Donnefort <vincent.donnefort@arm.com>,
	peterz@infradead.org, rjw@rjwysocki.net,
	vincent.guittot@linaro.org, qperret@google.com,
	linux-kernel@vger.kernel.org, ionela.voinescu@arm.com,
	dietmar.eggemann@arm.com
Subject: Re: [PATCH v2 0/3] EM / PM: Inefficient OPPs
Date: Wed, 26 May 2021 12:50:45 +0100	[thread overview]
Message-ID: <4a3db514-bec5-394f-ec3f-15c23b44b8f6@arm.com> (raw)
In-Reply-To: <fb80ceef-a2af-6f70-4863-fd376a438f3e@arm.com>



On 5/26/21 11:39 AM, Lukasz Luba wrote:
> 

[snip]

To summarize:
- we don't want to disable some OPPs
- we want to give a 'hint' from energy perspective
- we rely on SchedUtil 2nd stage which clamps this
freq hint value to allowed OPPs which might set
actually not the one what we see as 'efficient'
-- we don't harm some existing platform which might
    needs these 'inefficient' OPPs in some use cases
- we pay some extra cost in this SchedUtil freq
switch path, which shouldn't harm too much.
-- we pay this cost only for arm/arm64 platforms
    which use EM
-- this cost is balanced by the benefit that we see in
    benchmarks and measured energy
-- the LUT might limit the impact

I hope this would help to better understand the scope and
impact of this patch set.

Regards,
Lukasz

  reply	other threads:[~2021-05-26 11:52 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-21 16:54 [PATCH v2 0/3] EM / PM: Inefficient OPPs Vincent Donnefort
2021-05-21 16:54 ` [PATCH v2 1/3] PM / EM: Fix inefficient state detection Vincent Donnefort
2021-05-24 12:41   ` Lukasz Luba
2021-05-25  9:50   ` Quentin Perret
2021-05-21 16:54 ` [PATCH v2 2/3] PM / EM: Extend em_perf_domain with a flag field Vincent Donnefort
2021-05-24 12:44   ` Lukasz Luba
2021-05-25  9:54   ` Quentin Perret
2021-05-21 16:54 ` [PATCH v2 3/3] PM / EM: Skip inefficient OPPs Vincent Donnefort
2021-05-24 12:55   ` Lukasz Luba
2021-05-25  8:48   ` Peter Zijlstra
2021-05-25  9:21     ` Vincent Donnefort
2021-05-25 10:00       ` Vincent Donnefort
2021-05-28  5:09     ` Viresh Kumar
2021-06-01  8:47       ` Vincent Donnefort
2021-06-01  8:56         ` Viresh Kumar
2021-06-01  9:07           ` Quentin Perret
2021-06-01  9:13             ` Viresh Kumar
2021-05-25  9:33   ` Quentin Perret
2021-05-25  9:46     ` Vincent Donnefort
2021-05-25 11:03       ` Lukasz Luba
2021-05-25 13:06         ` Quentin Perret
2021-05-25 13:34           ` Lukasz Luba
2021-05-25  9:47     ` Vincent Donnefort
2021-05-28  5:04   ` Viresh Kumar
2021-05-28  9:00     ` Lukasz Luba
2021-05-26  3:47 ` [PATCH v2 0/3] EM / PM: Inefficient OPPs Viresh Kumar
2021-05-26  8:56   ` Lukasz Luba
2021-05-26  9:33     ` Viresh Kumar
2021-05-27  7:13       ` Lukasz Luba
2021-05-26  9:01   ` Vincent Donnefort
2021-05-26  9:38     ` Viresh Kumar
2021-05-26  9:39       ` Viresh Kumar
2021-05-26 10:24       ` Lukasz Luba
2021-05-26 10:39         ` Lukasz Luba
2021-05-26 11:50           ` Lukasz Luba [this message]
2021-05-26 13:49       ` Vincent Donnefort

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