Messages in this thread | | | Date | Tue, 21 Aug 2012 13:05:04 +0200 | Subject | Re: [discussion]sched: a rough proposal to enable power saving in scheduler | From | Vincent Guittot <> |
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On 21 August 2012 02:58, Alex Shi <alex.shi@intel.com> wrote: > On 08/20/2012 11:36 PM, Vincent Guittot wrote: > >>> > What you want it to keep track of a per-cpu utilization level (inverse >>> > of idle-time) and using PJTs per-task runnable avg see if placing the >>> > new task on will exceed the utilization limit. >>> > >>> > I think some of the Linaro people actually played around with this, >>> > Vincent? >> Sorry for the late reply but I had almost no network access during last weeks. >> >> So Linaro also works on a power aware scheduler as Peter mentioned. >> >> Based on previous tests, we have concluded that main drawback of the >> (now removed) old power scheduler was that we had no way to make >> difference between short and long running tasks whereas it's a key >> input (at least for phone) for deciding to pack tasks and for >> selecting the core on an asymmetric system. > > > It is hard to estimate future in general view point. but from hack > point, maybe you can add something to hint this from task_struct. :) >
per-task load tracking patchsets give you a good view of the last dozen of ms
>> One additional key information is the power distribution in the system >> which can have a finer granularity than current sched_domain >> description. Peter's proposal was to use a SHARE_POWERLINE flag >> similarly to flags that already describe if a sched_domain share >> resources or cpu capacity. > > > Seems I missed this. what's difference with current SD_SHARE_CPUPOWER > and SD_SHARE_PKG_RESOURCES.
SD_SHARE_CPUPOWER is set in a sched domain at SMT level (sharing some part of the physical core) SD_SHARE_PKG_RESOURCES is set at MC level (sharing some resources like cache and memory access)
> >> >> With these 2 new information, we can have a 1st power saving scheduler >> which spread or packed tasks across core and package > > > Fine, I like to test them on X86, plus SMT and NUMA :) > >> >> Vincent > >
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