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    Subject[PATCH 0/3] sched: Extend sched_mc/smt_power_savings framework.
    Date
    Hi,

    The following patch series extends the existing
    sched_smt/mc_power_savings framework to work on platforms that
    have onchip memory controller making each cpu package a 'node'

    On such machines with on-chip memory controller, each physical CPU
    package forms a NUMA node and the CPU level sched_domain will have
    only one group. This prevents any form of power saving balance across
    these nodes. Enabling the sched_mc/smt_power_savings tunable to work as
    designed on these new single CPU NUMA node machines will help task
    consolidation and save power as we did in other multi core multi
    socket platforms.

    Consolidation across NODES have implications of cross-node memory
    access and other NUMA locality issues. Even under such constraints
    there could be scope for power savings vs performance tradeoffs and
    hence making the sched_mc/smt_powersavings work as expected on these
    platform is justified.

    sched_mc/smt_power_savings is still a tunable and power savings benefits
    and performance would vary depending on the workload and the system
    topology and hardware features.

    The patch series has been tested on a 2-Socket Quad-core Dual threaded
    box with kernbench as the workload, varying the number of threads.

    The following results shows the average of 3 iterations of each of the runs.

    |-----------------------------------------------------------------------------|
    | testname | avg-time elapsed | % power consumed |
    |-----------------------------------------------------------------------------|
    | pm_kernbench.smt-0-mc-0_threads=4 | 95.28s | 100.00 |
    | pm_kernbench.smt-0-mc-1_threads=4 | 98.06s | 100.98 |
    | pm_kernbench.smt-0-mc-2_threads=4 | 99.14s | 101.98 |
    | pm_kernbench.smt-1-mc-1_threads=4 | 137.62s | 92.68 |
    | pm_kernbench.smt-1-mc-2_threads=4 | 142.75s | 91.89 |
    | pm_kernbench.smt-2-mc-2_threads=4 | 142.63s | 92.30 |
    |-----------------------------------------------------------------------------|
    | pm_kernbench.smt-0-mc-0_threads=6 | 66.25s | 100.00 |
    | pm_kernbench.smt-0-mc-1_threads=6 | 71.18s | 99.25 |
    | pm_kernbench.smt-0-mc-2_threads=6 | 69.43s | 100.12 |
    | pm_kernbench.smt-1-mc-1_threads=6 | 96.46s | 91.40 |
    | pm_kernbench.smt-1-mc-2_threads=6 | 99.51s | 90.49 |
    | pm_kernbench.smt-2-mc-2_threads=6 | 99.35s | 89.94 |
    |-----------------------------------------------------------------------------|
    | pm_kernbench.smt-0-mc-0_threads=7 | 58.20s | 100.00 |
    | pm_kernbench.smt-0-mc-1_threads=7 | 62.59s | 98.12 |
    | pm_kernbench.smt-0-mc-2_threads=7 | 60.73s | 99.17 |
    | pm_kernbench.smt-1-mc-1_threads=7 | 83.70s | 90.47 |
    | pm_kernbench.smt-1-mc-2_threads=7 | 83.31s | 88.98 |
    | pm_kernbench.smt-2-mc-2_threads=7 | 83.69s | 89.51 |
    |-----------------------------------------------------------------------------|
    | pm_kernbench.smt-0-mc-0_threads=8 | 54.08s | 100.00 |
    | pm_kernbench.smt-0-mc-1_threads=8 | 57.98s | 97.65 |
    | pm_kernbench.smt-0-mc-2_threads=8 | 55.79s | 99.28 |
    | pm_kernbench.smt-1-mc-1_threads=8 | 74.31s | 90.39 |
    | pm_kernbench.smt-1-mc-2_threads=8 | 76.03s | 89.88 |
    | pm_kernbench.smt-2-mc-2_threads=8 | 76.59s | 90.14 |
    |-----------------------------------------------------------------------------|
    | pm_kernbench.smt-0-mc-0_threads=9 | 51.67s | 100.00 |
    | pm_kernbench.smt-0-mc-1_threads=9 | 54.64s | 97.38 |
    | pm_kernbench.smt-0-mc-2_threads=9 | 52.78s | 98.81 |
    | pm_kernbench.smt-1-mc-1_threads=9 | 65.91s | 91.33 |
    | pm_kernbench.smt-1-mc-2_threads=9 | 66.93s | 91.36 |
    | pm_kernbench.smt-2-mc-2_threads=9 | 67.18s | 90.99 |
    |-----------------------------------------------------------------------------|


    Thoughts on this approach?

    ---

    Gautham R Shenoy (3):
    sched: Fix sd_parent_degenerate for SD_POWERSAVINGS_BALANCE.
    sched: Fix the wakeup nomination for sched_mc/smt_power_savings.
    sched: code cleanup - sd_power_saving_flags(), sd_balance_for_mc/package_power()


    include/linux/sched.h | 47 ++++++++++++++--------------------------
    include/linux/topology.h | 6 ++---
    kernel/sched.c | 54 +++++++++++++++++++++++++++++++++++++++++++---
    kernel/sched_fair.c | 2 +-
    4 files changed, 71 insertions(+), 38 deletions(-)

    --
    Thanks and Regards
    gautham.


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