Study sched_mc for Arm

Registered by Vincent Guittot on 2011-04-19

Study kernel topology/scheduling domain and cpu group for Arm platform. We must validate that topology is SoC independent. Then define what should be a topology for Arm SoC ( Take into account dual/quad/.. cores and next cortex generation)
Study how irq balancing and timer migration can help.

wiki page:https://wiki.linaro.org/WorkingGroups/PowerManagement/Specs/sched_mc

Blueprint information

Status:
Complete
Approver:
Amit Kucheria
Priority:
Essential
Drafter:
Vincent Guittot
Direction:
Approved
Assignee:
Vincent Guittot
Definition:
Approved
Series goal:
Accepted for trunk
Implementation:
Implemented
Milestone target:
milestone icon 2011.08
Started by
Amit Kucheria on 2011-06-03
Completed by
Mounir Bsaibes on 2011-09-20

Related branches

Sprints

Whiteboard

*Arm topology definition :
MIPDR register provides all thread/core/package info for Arm topology description
MPIDR register is accessed with MRC instruction
map MPIDR info on kernel topology

sched_mc uses topology description for creating sched_domain

*Timer and irq migration
available. need to check how/which pinned timer can impact power saving efficiency of sched_mc

*sched_mc
Default sched_domain init can be overwritten by arch specific one. Study if we need to define some arm specific
initializations

Work Items for 2011.08
[vincent-guittot] study impact flags and fields of struct sched_domain in scheduling policy: DONE
[vincent-guittot] study the interest of adding some arm platform dedicated SD_XXX_INIT configuration: DONE

these items were moved to https://blueprints.launchpad.net/linaro-pm-wg/+spec/sched-mc-for-arm
[robertdavidlee] read MPIDR register on Freescale multi-core platforms: TODO
[vincent-guittot] study the interest of changing topology with sched_mc mode: TODO
[vincent-guittot] study the pinned timer impact on sched_mc power mode: TODO
[vincent-guittot] study the interest of using FDT for cpu topology definition: TODO

(?)

Work Items

Work items for 2011.07:
[vincent-guittot] read MPIDR register on ST-Ericsson platforms: DONE
[amitdanielk] read MPIDR register on Samsung platforms: DONE
[vishwanath-bs] read MPIDR register on omap4 platforms: DONE
[lorenzo-pieralisi] read MPIDR register on ELBA platforms: DONE
[vincent-guittot] consolidate MPIDR register results: DONE
[vincent-guittot] define scheduling topology for ARM: DONE
[vincent-guittot] add default topology definition for Arm platform: DONE
[vincent-guittot] test default topology definition for Arm platform: DONE

Dependency tree

* Blueprints in grey have been implemented.

This blueprint contains Public information 
Everyone can see this information.