[PATCH 0/3] Improve EAS energy estimation and increase precision

From: Lukasz Luba
Date: Fri Jun 25 2021 - 11:26:41 EST

Hi all,

The patch set aims to address a scenario for Energy Aware Scheduler,
where we estimate and compare energy values and miss a more precised results.
In some use cases estimations for two CPUs might give the same values
for a given task and it's utilization. Those values would be different
when we have a better precision and avoid this rounding error.
Thus, the decision of choosing a CPU for a waking-up task might also
be better.

We have received this feedback from our partners.

Address this rounding error issue and increase the precision of Energy Model
em_perf_state::cost values. This change should not affect other
subsystems in kernel: thermal IPA, PowerCap DTPM, etc, since they use
em_perf_state::power field, which is not touched. It also doesn't
trigger the need for updating all existing platforms to register EM and report
power values in different scale.


Lukasz Luba (3):
sched/fair: Prepare variables for increased precision of EAS estimated
PM: EM: Make em_cpu_energy() able to return bigger values
PM: EM: Increase energy calculation precision

include/linux/energy_model.h | 11 +++++++----
kernel/power/energy_model.c | 3 ++-
kernel/sched/fair.c | 13 +++++++------
3 files changed, 16 insertions(+), 11 deletions(-)