From c4a6287185179732dfc1e903c195ff90c19f1065 Mon Sep 17 00:00:00 2001 From: Frode Isaksen Date: Tue, 19 Dec 2017 11:15:35 +0000 Subject: This layer provides Energy Aware Scheduling (EAS) patches For the moment only for Renesas R-Car Gen3 SoC's. Can be expanded for other SoC's by setting the machine feature biglittle and provide the relevant EAS patches. Bug-AGL: SPEC-813 Change-Id: I2b5e69c515c33e57be19b30466fe208d7b8ac1a5 Signed-off-by: Frode Isaksen --- meta-eas/README.md | 74 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 74 insertions(+) create mode 100644 meta-eas/README.md (limited to 'meta-eas/README.md') diff --git a/meta-eas/README.md b/meta-eas/README.md new file mode 100644 index 0000000..87494c4 --- /dev/null +++ b/meta-eas/README.md @@ -0,0 +1,74 @@ +# EAS patches for linux-reneas layer + +This README file contains information on the contents of the +meta-eas layer. + +Please see the corresponding sections below for details. + +### Dependencies +------------------------- + +This layer depends on: + + * URI: https://gerrit.automotivelinux.org/gerrit/AGL/meta-renesas-rcar-gen3
+ layers: `meta-rcar-gen3`
+ tag: `master` + +The machine feature `biglittle` must be set in order for these patches +to be applied. +If support in needed for another SoC, please add the machine feature +`biglittle` and provide the relevant EAS patches for the linux kernel. + +### Patches +----------- + +Please submit any patches against the meta-baylibre-agl-eas layer to the +the maintainers: + +* Michael Turquette +* Frode Isaksen +* Jerome Brunet + +## I. Description and provided packages: + +The layer provides Energy Aware Scheduling (EAS) patches for the linux-reneases kernel. +This package is an experimental utility to improve scheduling efficiency on big/LITTLE architecture. + ++ Patched packages : + - linux-renesas: Add configuration flags and patches required for EAS. + +## II. Adding the meta-baylibre-agl-eas layer to your AGL build + +1. Download meta-agl-extra at `$AGL_TOP` +2. Add `eas` to the feature of your AGL build
+```shell +source meta-agl/scripts/aglsetup.sh -m $MACHINE -b eas +``` + +With this `meta-eas` will be added to your `conf/bblayers.conf`. + +## III. Background information: + +Several techniques for saving energy through various scheduler +modifications have been proposed in the past, however most of the +techniques have not been universally beneficial for all use-cases and +platforms. For example, consolidating tasks on fewer cpus is an +effective way to save energy on some platforms, while it might make +things worse on others. + +This proposal, which is inspired by the Ksummit workshop discussions in +2013 [1], takes a different approach by using a (relatively) simple +platform energy cost model to guide scheduling decisions. By providing +the model with platform specific costing data the model can provide a +estimate of the energy implications of scheduling decisions. So instead +of blindly applying scheduling techniques that may or may not work for +the current use-case, the scheduler can make informed energy-aware +decisions. We believe this approach provides a methodology that can be +adapted to any platform, including heterogeneous systems such as ARM +big.LITTLE. The model considers cpus only, i.e. no peripherals, GPU or +memory. Model data includes power consumption at each P-state and +C-state. + +## IV. Further reading: + +https://developer.arm.com/open-source/energy-aware-scheduling -- cgit 1.2.3-korg