Wednesday 25/08/2010

This month's meetings

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IRC Nick

Amit Kucheria


Amit Arora


Vishwanath Sripathy


Bobby Bhatacharia


Srinivas Kalaga


Yong Shen



  • Review action items from last meeting
  • Blueprint status



Master blueprint for PM WG


PM Tools






Action Items from this Meeting

  • ACTION: Yong to work with John Rigby and Ubuntu kernel team to make sure the Linaro kernel contains powertop kernel patches
  • ACTION: Vishwa to verify powertop on 2.6.35
  • ACTION: Vishwa to check with cpuidle/cpufreq experts in TI for verifying cpufreq behavior on multi-core OMAP
  • ACTION: Amit A to get the powertop patch integrated into Linaro/Ubuntu packages
  • ACTION: Yong to test common clk API patches on imx5 and help get it booting on babbage 3.0

Action Items from Previous Meeting

  • ACTIVE (Immediate):
    • ACTION: Amit A to test on pm enabled OMAP3 board: DONE on 2.6.32 on zoom3 board
      • New ACTION: Vishwa to verify on 2.6.35
    • ACTION: Amit A to document details on power supply class (battery info) to PowerTOP internal wiki page: DONE
    • ACTION: Yong to look into getting powertop kernel patches applied to Linaro kernel tree: Not DONE
      • New ACTION: Yong to work with John Rigby and make sure the Linaro kernel contains it
    • ACTION: Robin to send links to patches sent to linux-pm: DONE
    • ACTION: Amit K to spend some time on usecase to reproduce ondemand governor problems: POSTPONED
    • ACTION: Yong to look at common clock FW, find out if debug info being exported (usage count, clk rate, dependencies): DONE
    • 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: Bobby to check on multi-core boards availability (request open)
    • 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


  • Discussion on

    • For ARM, both cores run at same frequency (CMP)
      • Does it make sense for them to run different governors on each core?
        • The consensus currently is NO
    • TI uses ondemand governor + policy manager
      • One core is kept OFF, all processing happen on the other one.
      • If load on one core goes above a threshold, they turn ON other core
      • Both cores run at same Operating Point once ON
  • Debug info in common clk API being discussed upstream by Jeremy
    • There is currently no debug info
    • clock name is not part of the common struct clk to keep size down
    • Need to engage with Jeremy
    • Yong will test the patches from Jeremy on imx5 and report back
  • Powerdebug: should we visualise the clock and power dependencies using information from /sys or debugfs?
    • No immediate horror expressed at the idea
    • Freescale and TI already do it to a certain extent by dumping the clock tree and rates into a table
    • The entire tree is too complex to depict
    • We could represent it in parts e.g. start at a peripheral and plot it's clock and power dependencies all the way up

WorkingGroups/PowerManagement/Meetings/2010-08-25 (last modified 2010-08-25 09:33:59)