Re: [Powertop] [PATCH 1/1] tunable: update sched_mc_power_savings target value

[Alexandra Yates <alexandra.yates at linux.intel.com>]

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> Hi Alexandra,
>
> Since we're going to require a later kernel, I think we should also remove
> the line that adds the (currently broken) sysfs_tunable for this feature
> as
> well.
>
> Cheers,
> Nanley
>
> On Mon, Sep 29, 2014 at 1:43 PM, Alexandra Yates <
> alexandra.yates(a)linux.intel.com> wrote:
>
>>
>> > On Fri, Aug 22, 2014 at 9:10 PM, Alexandra Yates <
>> > alexandra.yates(a)linux.intel.com> wrote:
>> >
>> >>
>> >> > On Tue, Aug 19, 2014 at 7:49 AM, Sergey Senozhatsky <
>> >> > sergey.senozhatsky(a)gmail.com> wrote:
>> >> >
>> >> >> On (08/13/14 21:28), Nanley Chery wrote:
>> >> >> > Starting in kernel 2.6.29, the highest power savings level
>> >> increased
>> >> >> to
>> >> >> "2".
>> >> >> > However, in kernel 3.5, the sched power savings feature was
>> removed
>> >> >> altogether.
>> >> >>
>> >> >> hello,
>> >> >> thanks for reporting,
>> >> >>
>> >> >>
>> >> >> so, it's been removed 2 years ago (3.5 release date was 21 Jul
>> 2012).
>> >> >>
>> >> >> do we need to support it at all?
>> >> >
>> >> >
>> >> > Hello,
>> >> >
>> >> > Good question. Our README file indicates linux-kernel >= 2.6.38 to
>> be
>> >> a
>> >> > build requirement. Does this mean we support power management
>> features
>> >> > starting from that kernel? Or does it mean that this is only a
>> build
>> >> > requirement and we target the latest kernels? It is not clear from
>> the
>> >> > current documentation.
>> >> >
>> >> > On a much smaller scope, supporting this feature is essentially
>> free
>> >> > (maintenance-wise) and would keep some of our end users on older
>> >> kernels
>> >> > happy. Btw, I submitted a simpler version 2 of this patch that does
>> >> not
>> >> > check for the kernel version.
>> >> >
>> >> > Thanks,
>> >> > Nanley
>> >> > _______________________________________________
>> >> > PowerTop mailing list
>> >> > PowerTop(a)lists.01.org
>> >> > https://lists.01.org/mailman/listinfo/powertop
>> >> >
>> >>
>> >> From PowerTOP 2.0 and up the requirement is to run at least Linux
>> kernel
>> >> 2.6.38. If it is not in the supported kernel then PowerTOP does not
>> need
>> >> it.
>> >>
>> >> Thank you,
>> >> Alexandra.
>> >>
>> >
>> > Since we're supporting kernels starting from 2.6.38 (which has this
>> power
>> > management feature itself), please consider this patch which produces
>> the
>> > correct behavior.
>> >
>> > Thanks,
>> > Nanley
>> >
>>
>> Hi Nanley,
>>
>> Thank you for your patch.  However, since this feature was faced out the
>> kernel over two years ago it doesn't make sense to add it now to
>> PowerTOP.
>> I will update the release notes to use a later kernel.  Please excuse
>> the
>> confusion.
>>
>> Thank you,
>> Alexandra.
>>
>>
>

This makes sense Nanley.  Since you have been working on this already,  Do
you want to send a patch with this change?

Thank you,
Alexandra.