linux-kernel - Re: [PATCH v2 0/6] sched: expel confusing usage of the term "power"

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Date:	Tue, 27 May 2014 16:07:15 +0200
From:	Daniel Lezcano <daniel.lezcano@...aro.org>
To:	Nicolas Pitre <nicolas.pitre@...aro.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>
CC:	Vincent Guittot <vincent.guittot@...aro.org>,
	Morten Rasmussen <morten.rasmussen@....com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	linux-kernel@...r.kernel.org, linaro-kernel@...ts.linaro.org
Subject: Re: [PATCH v2 0/6] sched: expel confusing usage of the term "power"

On 05/27/2014 12:19 AM, Nicolas Pitre wrote:
> "Power" is a very bad term in the scheduler context.  There are so many
> meanings that can be attached to it.  And with the upcoming "power
> aware" scheduler work, confusion is sure to happen.
>
> The definition of "power" is typically the rate at which work is performed,
> energy is converted or electric energy is transferred.  The notion of
> "compute capacity" is rather at odds with "power" to the point many
> comments in the code have to make it explicit that "capacity" is the
> actual intended meaning.
>
> So let's make it clear what we man by using "capacity" in place of "power"
> directly in the code.  That will make the introduction of actual "power
> consumption" concepts much clearer later on.
>
> This is based on the latest tip tree to apply correctly on top of existing
> scheduler changes already queued there.
>
> Changes from v1:
>
> - capa_factor and SCHED_CAPA_* changed to be spelled "capacity" in full
>    to save peterz some Chupacabra nightmares
>
> - some minor corrections in commit logs
>
> - rebased on latest tip tree
>
>
>   arch/arm/kernel/topology.c |  54 +++----
>   include/linux/sched.h      |   8 +-
>   kernel/sched/core.c        |  87 ++++++-----
>   kernel/sched/fair.c        | 323 ++++++++++++++++++++-------------------
>   kernel/sched/sched.h       |  18 +--
>   5 files changed, 246 insertions(+), 244 deletions(-)

Hi Nico,

it is a good initiative to replace the 'power' word by another to 
prevent confusion for future code. Personally I have a preference to 
'strength' instead of 'capacity', in case that matter.

Apart that:

Acked-by: Daniel Lezcano <daniel.lezcano@...aro.org>

Thanks
   -- Daniel


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