ACK: [SRU][N][PATCH v3 0/6] Update default Intel EPP Values

[Manuel Diewald]

On Wed, Sep 11, 2024 at 12:15:46AM -0300, Pedro Henrique Kopper wrote:
> BugLink: https://bugs.launchpad.net/bugs/2077470
> 
> SRU Justification:
> 
> [ Impact ]
> 
>  * Intel currently provides an Energy Performance Preference (EPP) tunable via its intel_pstate
>    to control power management. It ranges from 0 (performance) to 255 (powersaving).
>  * When the governor is set to powersave, which is the default, the EPP value of balance_performance
>    controls how the CPU frequency scaling occurs. However, on some platforms (Emerald Rapids, Meteor
>    Lake, Arrow Lake) it is set to a very conservative value out of the box, resulting in degraded
>    performance by default.
>  * These EPP tuning values work as a black-box and vary per-generation, so having the latest values
>    available is important to keep systems running at maximum achievable performance. Both Intel and
>    Canonical perform this kinds of tests and supply values.
> 
> [ Test Plan ]
> 
>  * Perform a benchmark on a stock Ubuntu 24.04 image
> 
>  * On Emerald Rapids:
>  * Change the EPP to 32 by executing
>    echo 32 | sudo tee /sys/devices/system/cpu/cpu*/cpufreq/energy_performance_preference
> 
>  * Observe the performance difference. In our internal testing, we found the following results
>    when setting EPP to 32:
>    POV-Ray: 32% faster | 12% less energy
>    OpenSSL: 12% faster | energy within 1%
>    Build Linux Kernel: 29% faster | 18% less energy
> 
>  * On Meteor Lake and Arrow Lake:
>  * Change the EPP to 64 by executing
>    echo 64 | sudo tee /sys/devices/system/cpu/cpu*/cpufreq/energy_performance_preference
> 
>  * Observe the performance difference. Intel found out the following for Meteor Lake:
>  > Speedometer 2.1
>  > score: +19%
>  > Perf/watt: +5.25%
>  >
>  > Webxprt 4 score
>  > score: +12%
>  > Perf/watt: +6.12%
>  >
>  > 3DMark Wildlife extreme unlimited score
>  > score: +3.2%
>  > Perf/watt: +11.5%
>  >
>  > Geekbench6 MT
>  > score: +2.14%
>  > Perf/watt: +0.32%
>  >
>  > Also update balance_power EPP default to 179. With this change:
>  > Video Playback power is reduced by 52%
>  > Team video conference power is reduced by 35%
>  * The same outcome should be obtained from Arrow Lake as per Intel.
> 
> [ Where problems could occur ]
> 
>  * The regression risks are very low. The CPU should perform in a more efficient zone, resulting in
>    overall power savings, despite the more aggressive scaling. This was verified using a Yokogawa WT310
>    power meter and an Emerald Rapids reference platform.
>  * Tests on Meteor Lake and Arrow Lake were performed by Intel. They were not independently verified by
>    Canonical.
> 
> [ Other Info ]
> 
>  * Patch for Emerald Rapids: https://lore.kernel.org/lkml/Zqu6zjVMoiXwROBI@capivara/ (merged in 6.11-rc3 https://lore.kernel.org/lkml/CAJZ5v0hQ3O7E3ygvFKbzjkJbx7pddyD9Qc+rE4EFYzJS12oTMg@mail.gmail.com/)
>  * Patch for Meteor Lake: https://lore.kernel.org/lkml/CAJZ5v0i8RnWs9OgxxqVOCG4RHhN7X3ELcruPoGrS1iP8hNSGsw@mail.gmail.com/ 
>  * Patch for Arrow Lake: https://lore.kernel.org/lkml/CAJZ5v0g+R6JK=T9EjmweRPKmcorw93JmPM4u-Z=pywv6kH7zUA@mail.gmail.com/ (both values for MTL and ARL merged in 6.11-rc1 https://lore.kernel.org/lkml/CAJZ5v0h7OHR7ipj6ubgTLEz238JZkTshh93CYe_gDx5j+zBwfA@mail.gmail.com/)
> 
> 
> Pedro Henrique Kopper (1):
>   cpufreq: intel_pstate: Update Balance performance EPP for Emerald
>     Rapids
> 
> Srinivas Pandruvada (4):
>   cpufreq: intel_pstate: Allow model specific EPPs
>   cpufreq: intel_pstate: Update default EPPs for Meteor Lake
>   cpufreq: intel_pstate: Update Meteor Lake EPPs
>   cpufreq: intel_pstate: Use Meteor Lake EPPs for Arrow Lake
> 
> Tony Luck (1):
>   cpufreq: intel_pstate: Switch to new Intel CPU model defines
> 
>  drivers/cpufreq/intel_pstate.c | 128 ++++++++++++++++++++-------------
>  1 file changed, 80 insertions(+), 48 deletions(-)
> 
> -- 
> 2.43.0
> 
> 
> -- 
> kernel-team mailing list
> kernel-team at lists.ubuntu.com
> https://lists.ubuntu.com/mailman/listinfo/kernel-team

Acked-by: Manuel Diewald <manuel.diewald at canonical.com>

-- 
 Manuel
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