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    SubjectRe: [Results] [RFC PATCH v4 00/40] mm: Memory Power Management
    >>>>
    >>>
    >>> Arjan, are you referring to the fact that Intel/SNB systems can exploit
    >>> memory self-refresh only when the entire system goes idle? Is that why
    >>> this
    >>> patchset won't turn out to be that useful on those platforms?
    >>
    >> no we can use other things (CKE and co) all the time.
    >>
    >
    > Ah, ok..
    >
    >> just that we found that statistical grouping gave 95%+ of the benefit,
    >> without the cost of being aggressive on going to a 100.00% grouping
    >>
    >
    > And how do you do that statistical grouping? Don't you need patches similar
    > to those in this patchset? Or are you saying that the existing vanilla
    > kernel itself does statistical grouping somehow?

    so the way I scanned your patchset.. half of it is about grouping,
    the other half (roughly) is about moving stuff.

    the grouping makes total sense to me.
    actively moving is the part that I am very worried about; that part burns power to do
    (and performance).... for which the ROI is somewhat unclear to me
    (but... data speaks. I can easily be convinced with data that proves one way or the other)

    is moving stuff around the 95%-of-the-work-for-the-last-5%-of-the-theoretical-gain
    or is statistical grouping enough to get > 95% of the gain... without the cost of moving.


    >
    > Also, I didn't fully understand how NUMA policy will help in this case..
    > If you want to group memory allocations/references into fewer memory regions
    > _within_ a node, will NUMA policy really help? For example, in this patchset,
    > everything (all the allocation/reference shaping) is done _within_ the
    > NUMA boundary, assuming that the memory regions are subsets of a NUMA node.
    >
    > Regards,
    > Srivatsa S. Bhat
    >



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