EAS Development for Mainline Linux

EAS development for mainline Linux takes place on LKML and Linaro eas-dev mailing lists where proposed patches are discussed with the community. Arm now provides a pre-integrated version of latest EAS patches for mainline, for upstream development use.

EAS mainline is a moving integration branch tracking tip:sched/core and adding the latest versions of EAS related patch sets targeted at the mainline kernel. The patches may already be under discussion on relevant open source mailing lists or waiting here while their dependencies get resolved and merged upstream.

The integration branch comes as is with synthetic test case testing only. The intention is to have a single branch containing the full EAS picture for mainline Linux kernel developers interested in tracking progress. This EAS mainline integration branch is not suitable for product development. For product, please use the AOSP common kernel.

Source code

EAS mainline integration branches are made available regularly on:


The releases are tagged with the date e.g. _20180622 so old integrations are available for comparison

Latest: integration_20190208

Tree: eas/next/integration

Base: eas/next/integration_base

New changes:

  1. Per-cpu Energy Model and Energy Aware Scheduling now in v5.0-rc5.


  1. Per-cpu Energy Model and Energy Aware Scheduling.
  2. Util(ization) clamping, i.e. a mechanism which allows to "clamp" (i.e. filter) the utilization generated by RT and FAIR task within a range defined from user-space.
  3. Periodic load balance improvements.
  4. Tracepoints.

Features now in mainline:

  1. Frequency Invariant Engine (FIE) and CPU Invariant Engine (v4.13/v4.15).
  2. Idle CPU PELT (Per-Entity Load-Tracking) update (v4.17).
  3. Util(ization) Est(imated) (v4.17).
  4. Misfit task, i.e. forcing migration of running tasks that do not fit on the CPU they are currently running on (v4.20).
  5. Runtime scheduler domain flag detection (v4.20).

Supported platforms:

  1. Arm Juno r0
  2. Arm Juno r2
  3. Hikey960 (needs out-of-tree patches, provided by the hikey960_mainline topic branch which comes with this integration)
  4. Arm TC2

Next work items:

Work on getting a 100% pass-rate on all platforms (Arm Juno r0/r2, Hikey960 and Arm TC2).

  • Test Results (integration 20190208)
    • platform Juno r0
    • test case passed if failure rate < 10%
    • EAS behaviour:

                                                                          pass rate
      EnergyModelWakeMigration: test_slack:               passed  163/163 (100.0%)
      EnergyModelWakeMigration: test_task_placement: passed 163/163 (100.0%)
      OneSmallTask: test_slack: passed 163/163 (100.0%)
      OneSmallTask: test_task_placement: passed 163/163 (100.0%)
      RampDown: test_slack: passed 163/163 (100.0%)
      RampDown: test_task_placement: passed 163/163 (100.0%)
      RampUp: test_slack: passed 163/163 (100.0%)
      RampUp: test_task_placement: passed 163/163 (100.0%)
      ThreeSmallTasks: test_slack: passed 163/163 (100.0%)
      ThreeSmallTasks: test_task_placement: passed 160/163 ( 98.2%)
      TwoBigTasks: test_slack: passed  158/163 ( 96.9%)
      TwoBigTasks: test_task_placement: passed 163/163 (100.0%)
      TwoBigThreeSmall: test_slack: FAILED 7/163 ( 4.3%)
      TwoBigThreeSmall: test_task_placement: FAILED  7/163 ( 4.3%)

    • load tracking:

                                                                          pass rate
      CpuInvarianceTest:        test_task_util_avg:       passed  164/164 (100.0%)
      FreqInvarianceTest: test_task_load_avg: passed 163/164 ( 99.4%)
      FreqInvarianceTest: test_task_util_avg: passed 163/164 ( 99.4%)
      OneTaskCPUMigration: test_util_task_migration: passed 164/164 (100.0%) PELTTasksTest: test_load_avg_behaviour: passed 153/164 ( 93.3%)
      PELTTasksTest: test_load_avg_range: passed 164/164 (100.0%)
      PELTTasksTest: test_util_avg_behaviour: passed 155/164 ( 94.5%)
      PELTTasksTest: test_util_avg_range: passed 164/164 (100.0%)
      TwoTasksCPUMigration: test_util_task_migration: passed 164/164 (100.0%)
    • misfit:

                                                                          pass rate
      StaggeredFinishes:        test_migration_delay:     passed  162/163 ( 99.4%)
      StaggeredFinishes: test_preempt_time: passed 162/163 ( 99.4%)
      StaggeredFinishes: test_throughput: passed  162/163 ( 99.4%)