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    SubjectRe: [RFC PATCH v4 00/14] sched: packing small tasks
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    On 26 April 2013 17:00, Arjan van de Ven <arjan@linux.intel.com> wrote:
    > On 4/25/2013 10:23 AM, Vincent Guittot wrote:
    >>
    >> Hi,
    >>
    >> This patchset takes advantage of the new per-task load tracking that is
    >> available in the kernel for packing the tasks in as few as possible
    >> CPU/Cluster/Core. It has got 2 packing modes:
    >> -The 1st mode packs the small tasks when the system is not too busy. The
    >> main
    >> goal is to reduce the power consumption in the low system load use cases
    >> by
    >> minimizing the number of power domain that are enabled but it also keeps
    >> the
    >> default behavior which is performance oriented.
    >> -The 2nd mode packs all tasks in as few as possible power domains in order
    >> to
    >> improve the power consumption of the system but at the cost of possible
    >> performance decrease because of the increase of the rate of ressources
    >> sharing
    >> compared to the default mode.
    >
    >
    >
    > so I got to ask the hard question; what percentage of system level (not just
    > cpu level)
    > power consumption gain can you measure (pick your favorite workload)...
    >

    I haven't system level figures for my patches but only for the cpu
    subsystem. If we use the MP3 results in the back of my mail, they show
    an improvement of 37 % (113/178) for the CPU subsystem of the
    platform. If we assume that the CPU subsystem contributes 25% of an
    embedded system power consumption (this can vary across platform
    depending of the use of HW accelerator but it should be a almost fair
    percentage), the patch can impact the power consumption on up to 9%.

    > on x86 (even on the low power stuff) I expect this to be very far into the
    > noise
    > (since we have per core power gates, and power transitions are pretty fast)
    >
    > you have some numbers in the back of your mail, but it's hard for me to get
    > a conclusion out of
    > that (they either measure only cpu power, or are just vague in general)
    >
    >
    > --
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