https://wiki.linaro.org/projects/big.LITTLE.MP
Work Items for functional completion: https://wiki.linaro.org/projects/big.LITTLE.MP/WorkItems
Main Project page: https://launchpad.net/linaro-big-little-system
Development ============
1. big.LITTLE IKS
IKS snapshot: git://git.linaro.org/landing-teams/working/arm/kernel.git
More information: http://lists.linaro.org/pipermail/linaro-dev/2013-May/015882.html
Also the latest Linaro 13.05 release contains big.LITTLE release with IKS code integrated. By default MP is used (IKS is off). To enable IKS:
echo 1 > /sys/kernel/bL_switcher/active
2. big.LITTLE MP
There are two branches, which are functionally equivalent - they tweak the scheduler to select the right processes to move to the A15 and try to decrease power consumption while maintaining performance.
* A Reference (stable) big.LITTLE MP patchset (merged with linux-linaro):
https://git.linaro.org/gitweb?p=arm/big.LITTLE/mp.git%3Ba=shortlog%3Bh=refs/...
Recommended to be used for testing.
* And an upstream (work in progress) big.LITTLE MP patchset:
https://git.linaro.org/gitweb?p=arm/big.LITTLE/mp.git%3Ba=shortlog%3Bh=refs/...
Being worked on in order to achieve the performance/power numbers of the reference one. Upstream discussion is ongoing.
* Documentation:
Code flow is already covered by several LWN articles. See https://wiki.linaro.org/WorkingGroups/PowerManagement/Doc/ in the Articles section. We will provide a tuning guide once we have reached agreement upstream.
* Automated benchmarking code is ready:
- Golden Board is to be used for running daily tests. - Both branches - reference and upstream to be tested.
Blueprint Updates ------------------
* https://blueprints.launchpad.net/linaro-big-little-system/+spec/big-little-m...
Ongoing work.
* https://blueprints.launchpad.net/linaro-big-little-system/+spec/small-task-p...
- Trying to understand the diff reference/upstream with dbench. - Workbench modified to get more information. - Big variation of results is visible (page rendering). - Official test on the Golden Board is to be done. - v5 upstreaming is postponed.
* https://blueprints.launchpad.net/linaro-big-little-system/+spec/sched-cooper...
- Postponed. Priorities are to be re-evaluated.
QA ==
big.LITTLE MP LAVA Dashboard http://validation.linaro.org/lava-server/dashboard/image-reports/linaro-andr...
Testing (week 23):
sched_tests.git #Cases #Run Pass Fail Absolute pass rate Regression 20 19 19 0 100 % mpbasicsuite 14 10 10 0 100 % mpcoresuite 10 6 6 0 84 % [1] mpextendedsuite 20 10 7 3 70 % [2] mploadbalance 2 2 2 0 100 %
--- [1] https://bugs.launchpad.net/linaro-big-little-system/+bug/1188655 [2] https://bugs.launchpad.net/linaro-big-little-system/+bug/1183769
Bugs: https://bugs.launchpad.net/linaro-big-little-system/+bugs?field.tag=bl-mp
Highlight: Bug 1166246 - Lockup on post 3.9 IKS kernel
- can be hardware or software bug, investigation continues. - seems to be related to MMC being in use (switching to USB stick can be used as a reliable workaround).
Highlight: Bug 1183821 - perf failed to count events on A15 cluster
- existing perf code is at the end of it's lifecycle. - a rewrite is ongoing. - will most likely stay unfixed for Linaro 13.6 release.