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    SubjectRe: [PATCH v7 0/8] Tunable sched_mc_power_savings=n

    * Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com> wrote:

    > Hi,
    >
    > The existing power saving loadbalancer CONFIG_SCHED_MC attempts to run
    > the workload in the system on minimum number of CPU packages and tries
    > to keep rest of the CPU packages idle for longer duration. Thus
    > consolidating workloads to fewer packages help other packages to be in
    > idle state and save power. The current implementation is very
    > conservative and does not work effectively across different workloads.
    > Initial idea of tunable sched_mc_power_savings=n was proposed to enable
    > tuning of the power saving load balancer based on the system
    > configuration, workload characteristics and end user requirements.
    >
    > The power savings and performance of the given workload in an under
    > utilised system can be controlled by setting values of 0, 1 or 2 to
    > /sys/devices/system/cpu/sched_mc_power_savings with 0 being highest
    > performance and least power savings and level 2 indicating maximum power
    > savings even at the cost of slight performance degradation.
    >
    > Please refer to the following discussions and article for details.
    >
    > [1]Making power policy just work
    > http://lwn.net/Articles/287924/
    >
    > [2][RFC v1] Tunable sched_mc_power_savings=n
    > http://lwn.net/Articles/287882/
    >
    > v2: http://lwn.net/Articles/297306/
    > v3: http://lkml.org/lkml/2008/11/10/260
    > v4: http://lkml.org/lkml/2008/11/21/47
    > v5: http://lkml.org/lkml/2008/12/11/178
    > v6: http://lwn.net/Articles/311830/
    >
    > The following series of patch demonstrates the basic framework for
    > tunable sched_mc_power_savings.
    >
    > This version of the patch incorporates comments and feedback received
    > on the previous post from Andrew Morton.
    >
    > Changes form v6:
    > ----------------
    > * Convert BALANCE_FOR_xx_POWER and related macros to inline functions
    > based on comments from Andrew and Ingo.
    > * Ran basic kernelbench test and did not see any performance variation
    > due to the changes.
    >
    > Changes form v5:
    > ---------------
    > * Fixed the sscanf bug and checking for (p->flags & PF_KTHREAD)
    > * Dropped the RFC prefix to indicate that the patch is ready for
    > testing and inclusion
    > * Patch series against 2.6.28-rc8 kernel

    thanks, applied - and i started testing them. It needed some help here and
    there to resolve conflicts with pending cpumask changes. Could you please
    double-check the merged up end result in the latest scheduler devel tree:

    http://people.redhat.com/mingo/tip.git/README

    thanks,

    Ingo


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