NACK/Cmnt: [SRU][N][PATCH 0/5] Update default Intel EPP Values

[Thibault Ferrante]

On 30-08-2024 09:52, Stefan Bader wrote:
> On 28.08.24 21:41, Pedro Henrique Kopper wrote:
>> BugLink: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/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 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
>>
>>   drivers/cpufreq/intel_pstate.c | 46 +++++++++++++++++++++++++++++-----
>>   1 file changed, 40 insertions(+), 6 deletions(-)
>>
> 
> Rejected for the following reasons:
> - BugLink has to be in every patch and follow standard format
> 
> BugLink: https://bugs.launchpad.net/bugs/<id>
> 
> -Stefan
> 

Can you add the [SRU][N] to every patch subject ?
Also, you should specify the provenance for every patch.
It should look like :
(cherry-picked from commit XXXX)
Signed-off-by: XXXX XXXX <XXX.XXX at canonical.com>



-- 
--
Thibault