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    SubjectRe: [PATCH v7 0/8] Tunable sched_mc_power_savings=n
    * Balbir Singh <balbir@linux.vnet.ibm.com> [2008-12-30 08:18:19]:

    > * MinChan Kim <minchan.kim@gmail.com> [2008-12-30 08:43:58]:
    >
    > > Hi, Vaidyanathan.
    > > It's very late reponse. :(
    > >
    > > > Results:
    > > > --------
    > > >
    > > > Basic functionality of the code has not changed and the power vs
    > > > performance benefits for kernbench are similar to the ones posted
    > > > earlier.
    > > >
    > > > KERNBENCH Runs: make -j4 on a x86 8 core, dual socket quad core cpu
    > > > package system
    > > >
    > > > SchedMC Run Time Package Idle Energy Power
    > > > 0 81.68 52.83% 54.71% 1.00x J 1.00y W
    > > > 1 80.70 36.62% 70.11% 0.95x J 0.96y W
    > > > 2 74.95 19.53% 85.92% 0.90x J 0.98y W
    > > >
    > > > The results are marginally better than the previous version of the
    > > > patch series which could be within the test variation.
    > > >
    > > > Please feel free to test, and let me know your comments and feedback.
    > > > I will post more experimental results with various benchmarks.
    > >
    > > Your result is very interesting.
    > > level 2 is more fast and efficient of power.
    > >
    > > What's major contributor to use less time in level 2?
    > > I think it's cache bounce is less time than old.
    > > Is right ?
    > >
    >
    > Yes, correct
    >
    > > I want to test SCHED_MC but I don't know what you use to benchmark about power.
    > > How do I get the data about 'Package, Idle, Energy, Power'?
    > >
    >
    > Note, it is Package Idle (for both packages), it is a x86-64 8 core,
    > dual socket, quad core box. It is not Package, Idle.
    >
    > For Energy and Power you need a means of measuring power like a meter.
    >

    Hi MinChan,

    Thank you for your interest in sched_mc power saving feature. As
    Balbir has mentioned, you will need a power measurement infrastructure
    like an external power meter.

    Laptops have battery discharge rate measurement that is a good
    approximation for power consumption. But that is not helpful to test
    sched_mc since we would need a multi-socket multi core system to get
    power saving benefit from the enhancements.

    The 'package idle' information comes from /proc/stat by adding up the
    idle times from various logical CPUs belonging to a single physical
    package. All logical CPUs belonging to a single physical package can
    be identified from /proc/cpuinfo or
    /sys/devices/system/cpu/cpu<n>/topology/physical_package_id

    --Vaidy


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