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sched: unified sched_powersavings tunables

From:  Vaidyanathan Srinivasan <>
To:  Vincent Guittot <>, Peter Zijlstra <>, Indan Zupancic <>, Youquan Song <>, Ingo Molnar <>, Arjan van de Ven <>, Suresh Siddha <>
Subject:  [RFC PATCH v1 0/2] sched: unified sched_powersavings tunables
Date:  Mon, 16 Jan 2012 21:52:26 +0530
Message-ID:  <20120116161740.29759.4679.stgit@localhost>
Cc:  Linux Kernel <>
Archive-link:  Article


I have created the following RFC patch based on the recent discussions
and consensus on simplifying the power aware scheduler in the kernel.

Ref: LWN: Rethinking power-aware scheduling

The goal of the unified tunable are as follows:

* Simple and single tunable for different (all) topology
* Good default powersavings for kernel
* Potential to map this setting to other subsystems like cpufreq and

What this patch does: (first step)

* Create a single sched_powersavings tunable in sysfs
* Enable current sched_mc and sched_smt features based on 
  value of this single tunable

What this patch is yet to do:

* Tune the default power savings to pack packages only till
  a threshold of say 50%
* Add notifiers to change setting on battery/AC transitions
* Feed the thresholds from arch specific code so that different archs
  can do 'optimal' packing based on topology  
* May be move this to /sys/device/system/powersavings and add additional
  platform tunables like x86_energy_perf_policy?

This RFC has only x86 changes and has been tested on dual-socket,
quad-core,HT configuration.

Please let me know your comments and feedback.



Vaidyanathan Srinivasan (2):
      sched: unified sched_powersavings sysfs tunable
      sched: fix group_capacity for thread level consolidation

 arch/x86/Kconfig          |   20 ++++--------
 arch/x86/kernel/smpboot.c |    2 +
 block/blk.h               |   11 ++++---
 drivers/base/cpu.c        |    2 +
 include/linux/sched.h     |   29 +++++++++--------
 include/linux/topology.h  |    9 +----
 kernel/sched/core.c       |   75 +++++++++++----------------------------------
 kernel/sched/fair.c       |   38 ++++++++++++++++-------
 8 files changed, 77 insertions(+), 109 deletions(-)

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