Re: [RFCv3 PATCH 00/48] sched: Energy cost model for energy-aware scheduling

[Vincent Guittot]

On 8 April 2015 at 15:33, Morten Rasmussen <morten.rasmussen@xxxxxxx> wrote:
> Hi Vincent,
>
> On Thu, Apr 02, 2015 at 01:43:31PM +0100, Vincent Guittot wrote:
>> On 4 February 2015 at 19:30, Morten Rasmussen <morten.rasmussen@xxxxxxx> wrote:
>> > RFCv3 is a consolidation of the latest energy model related patches and
>> > previously posted patch sets related to capacity and utilization
>> > tracking [2][3] to show where we are heading. [2] and [3] have been
>> > rebased onto v3.19-rc7 with a few minor modifications. Large parts of
>> > the energy model code and use of the energy model in the scheduler has
>> > been rewritten and simplified. The patch set consists of three main
>> > parts (more details further down):
>> >
>> > Patch 1-11:  sched: consolidation of CPU capacity and usage [2] (rebase)
>> >
>> > Patch 12-19: sched: frequency and cpu invariant per-entity load-tracking
>> >                     and other load-tracking bits [3] (rebase)
>> >
>> > Patch 20-48: sched: Energy cost model for energy-aware scheduling (RFCv3)
>>
>>
>> Hi Morten,
>>
>> 48 patches is a big number of patches and when i look into your
>> patchset, some feature are quite self contained. IMHO it would be
>> worth splitting it in smaller patchsets in order to ease the review
>> and the regression test.
>> From a 1st look at your patchset , i have found
>> -patches 11,13,14 and 15 are only linked to frequency scaling invariance
>> -patches 12, 17 and 17 are only about adding cpu scaling invariance
>> -patches 18 and 19 are about tracking and adding the blocked
>> utilization in the CPU usage
>> -patches 20 to the end is linked the EAS
>
> I agree it makes sense to regroup the patches as you suggest. A better
> logical ordering should make the reviewing a less daunting task. I'm a
> bit hesitant to float many small sets of patches as their role in the
> bigger picture would be less clear and hence risk loosing the 'why'.
> IMHO, it should be as easy (if not easier) to review and pick patches in
> a larger set as it is for multiple smaller sets. However, I guess that

Having self contained patchset merged in a larger set  can create so
useless dependency between them as they modify same area but for
different goal

> is individual and for automated testing it would be easier to have them
> split out.
>
> How about focusing on one (or two) of these smaller patch sets at the
> time to minimize the potential confusion and post them separately?

I'm fine with your proposal to start with 1 or 2 smaller patchset. The
2 following patchset are, IMHO, the ones the most self contained and
straight forward:
- patches 11,13,14 and 15 are only linked to frequency scaling invariance
- patches 18 and 19 are about tracking and adding the blocked
utilization in the CPU usage

May be we can start with them ?

Regards,
Vincent

>
> I would still include them in updated mega-postings that includes all
> the dependencies so the full story would still available for those who
> are interested. I would of course make it clear which patches that are
> also posted separately.

that's fair enough

>
> Thanks,
> Morten
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