APPLIED[L]: [SRU U/L/K/J] Adjust balanced governor for Sappire Rapids

[Andrea Righi]

On Fri, Mar 10, 2023 at 11:53:21AM +0100, Stefan Bader wrote:
> BugLink: https://bugs.launchpad.net/bugs/2008519
> 
> The goal is to adjust the behavior of the balanced governor for certain Xeon
> CPUs (those are CPUs rather seen in servers so there should be no impact on
> laptop users). While the initial request was Jammy/5.15 only we should do
> this to Kinetic and Lunar as well so the experience is the same regardless of
> release.
> 
> == Fix ==
> This picks one change from v6.3-rc1 which tweaks the intel_idle driver for a
> specific CPU model. For Jammy/5.15 this requires one additional change
> which introduces the EPP tweak for Alderlake.
> 
> == Regression Potential ==
> The change modifies how quickly CPUs scale up (and probably down) depending on
> workload. Power usage unlikely is of that much concern in server space. Maybe
> increased heat would be observed.
> For Jammy there is the additional risk of havind a different power usage
> on Alderlake which is a Laptop CPU. However that change is part of v5.17
> and thus would already be in effect with current 22.04 HWE.

Applied to lunar/linux.

Thanks,
-Andrea