• Linus Torvalds's avatar
    Merge branch 'for-3.11' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq · f317ff9e
    Linus Torvalds authored
    Pull workqueue changes from Tejun Heo:
     "Surprisingly, Lai and I didn't break too many things implementing
      custom pools and stuff last time around and there aren't any follow-up
      changes necessary at this point.
    
      The only change in this pull request is Viresh's patches to make some
      per-cpu workqueues to behave as unbound workqueues dependent on a boot
      param whose default can be configured via a config option.  This leads
      to higher processing overhead / lower bandwidth as more work items are
      bounced across CPUs; however, it can lead to noticeable powersave in
      certain configurations - ~10% w/ idlish constant workload on a
      big.LITTLE configuration according to Viresh.
    
      This is because per-cpu workqueues interfere with how the scheduler
      perceives whether or not each CPU is idle by forcing pinned tasks on
      them, which makes the scheduler's power-aware scheduling decisions
      less effective.
    
      Its effectiveness is likely less pronounced on homogenous
      configurations and this type of optimization can probably be made
      automatic; however, the changes are pretty minimal and the affected
      workqueues are clearly marked, so it's an easy gain for some
      configurations for the time being with pretty unintrusive changes."
    
    * 'for-3.11' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
      fbcon: queue work on power efficient wq
      block: queue work on power efficient wq
      PHYLIB: queue work on system_power_efficient_wq
      workqueue: Add system wide power_efficient workqueues
      workqueues: Introduce new flag WQ_POWER_EFFICIENT for power oriented workqueues
    f317ff9e
workqueue.c 138 KB