Wednesday, 20-10-2010




IRC Nick

Amit Kucheria


Amit Arora


Vishwanath Sripathy


Yong Shen


Vincent Guittot


Amit Kachhap


Bobby Bhatacharia


Srinivas Kalaga


Robin Randhawa



  • People
  • Review action items from last meeting
  • Weekly reports

  • Blueprint status: List of blueprints

  • 11.05 cycle updates
    • Blueprints, work items
  • Miscellaneous topics

Action Items from this Meeting

  • Yong: email list on finding from thermal frameworks study

Action Items from Previous Meeting

  • Immediate:
    • Robin: Get back with details on how to split access into secure and non-secure context: PENDING
    • Everyone: Breakdown the blueprints assigned to you into work items: DONE
    • Srinivas: Talk inside ARM about making context save/restore code available: DONE
    • Yong: Make sure all blueprints under meta-miscellaneous have work items: DONE
    • Vincent: Make sure all blueprints under meta-multicore have work items: DONE
    • Vishwa: Make sure all blueprints under meta-cpuidle have work items: DONE
    • Amit K: Make sure all blueprints under meta-cpufreq have work items: DONE
    • ACTION: ARM: results of using PMU counters for correlation to PM
    • ACTION: Amit K to spend some time on usecase to reproduce ondemand governor problems: POSTPONED
    • Amit K (added post meeting): looking into merging linux-pm branch for OMAP into Linaro
    • ACTION: ARM to share internal instrumentation flow (BAB: we might also align with Linaro on workload discussions)
      • Might take couple of months
    • ACTION: Amit K to talk to jeremy about power domain framework: DONE
      • Jeremy needs help, will revisit in a few weeks
    • ACTION: Srinivas to provide details of where he believes userspace - kernel interaction is required. (low prio)
    • ACTION: ARM to discuss giving out internal Eclipse based tool (similar to powertop) (no ETA as of now)
    • ACTION: Amit Kucheria and Vishwa to get inputs from community on the issues related to CPUIDLE governor: POSTPONED until instrumentation work


  • No call next week due to LDS
  • Those not attending can listen to audio streams
    • Confirm that the time-slots are fine and inform Amit K. to see if some slots can be moved around
  • ARM trying to open up context save/restore code soon (4+ weeks)
  • Ondemand governor performance problems discussed in detail
    • Performance is reduced by 80% with ondemand governor compared to performance governor in I/O bound USB transfer usecase
    • problem persists even after increasing ondemand sampling frequency
    • CPU load is very low during the I/O, so ondemand doesn't scale up
    • However, setting the min_freq knob with ondemand improves performance - so cpu frequency does have an effect on the transfer
    • Interconnect speed was kept constant, so reduced frequency shouldn't affect it
    • So we have two different problems now - one related to ondemand not accounting for I/O bound processes, other ondemand not scaling fast enough for cpu-bound processes.
  • Welcome Amit Daniel from Samsung to PMWG

WorkingGroups/PowerManagement/Meetings/2010-10-20 (last modified 2010-10-20 09:30:00)