On 6 September 2011 17:38, Amit Kucheria <amit.kuche...@linaro.org> wrote: > On Fri, Sep 2, 2011 at 6:07 PM, Christian Robottom Reis <k...@linaro.org> > wrote: >> On Thu, Sep 01, 2011 at 02:22:03PM -0500, Mounir Bsaibes wrote: >>> * Made hotplug power measurements on st-e u8500 platform >>> * mp3 playback test showed between 7 to 8% power improvement >>> * cpuhotplug - For Linux idle case, no visible improvement as power is >>> already very low >> >> This is using hotplug versus plain cpuidle -- and if so, does this mean >> that the proper fix is extending cpuidle to go to the lowest power state? > > It isn't extending cpuidle but more like implementing the cpuidle > platform-specific driver correctly. > > What I find more interesting is that a low-power mp3 usecase (display > off, play mp3 at half volume, etc.) still saves 7-8% with hotplug. > It'd be worth looking at the scheduler traces to see if the second > core is coming into play in the mp3 usecase. Vincent? >
MP3 uses 2 cpus when they are both onlines. Using 1 cpu provides the best powersaving results mainly because we don't need and use the full power of the dual CA-9. Now, I currently trying to reach the same results with the right scheduler and topology configuration instead of unplugging cpu1. It's on going but I need to play with optimized old kernel and latest non optimized one. >>> * Re-writing cpuidle driver >> >> For which platforms? > > For i.MX5. Rob what is the status of posting this to the list? > _______________________________________________ linaro-dev mailing list linaro-dev@lists.linaro.org http://lists.linaro.org/mailman/listinfo/linaro-dev
