linux-kernel - Re: [PATCH v2 3/3] cpufreq: intel_pstate: hybrid: Adjust energy model rules

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Message-ID: <1592aa65-9dfb-47d6-9bcf-17afd3184a0a@arm.com>
Date: Thu, 16 Oct 2025 15:59:09 +0200
From: Dietmar Eggemann <dietmar.eggemann@....com>
To: "Rafael J. Wysocki" <rafael@...nel.org>,
 Christian Loehle <christian.loehle@....com>
Cc: Yaxiong Tian <tianyaxiong@...inos.cn>, linux-kernel@...r.kernel.org,
 linux-pm@...r.kernel.org, lukasz.luba@....com,
 srinivas.pandruvada@...ux.intel.com
Subject: Re: [PATCH v2 3/3] cpufreq: intel_pstate: hybrid: Adjust energy model
 rules

On 16.10.25 11:52, Rafael J. Wysocki wrote:
> On Thu, Oct 16, 2025 at 11:00 AM Christian Loehle
> <christian.loehle@....com> wrote:
>>
>> On 10/16/25 08:48, Yaxiong Tian wrote:
>>> 在 2025/10/15 21:48, Rafael J. Wysocki 写道:> From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

[...]

>>> Hi Rafael J. Wysocki:
>>>
>>> Is the increment of this cost for different types of CPUs by one instead
>>> of two?
>>>
>>> cost by increment of 2:
>>>           0~40%  40%~60%  60%~80% 80%~100
>>> LPE-core    2       3        4      5
>>> E-core      4       5        6      7
>>> P-core      6       7        8      9
>>>
>>> So, tasks only start being allocated to more powerful CPUs when
>>> utilization exceeds 80%, but by that point the system is already in an
>>>  overloaded state.
>>>
>>> cost by increment of 1:
>>>           0~40%  40%~60%  60%~80% 80%~100
>>> LPE-core    2       3        4      5
>>> E-core      3       4        5      6
>>> P-core      4       5        6      7
>>>
>>> This situation aligns with the description in your patch.
>>>
>>> The idea of this patch looks good to me.
>>
>> Agreed if you want the threshold to be 60% for both it should be +1 for l3
>> and +2 for P-core.
>> Good catch!
> 
> OK, I'll send an update of this patch then, but I won't resend the
> first two patches in the series.  I don't think that they are
> objectionable.

FWIW: LGTM: tested on i7-13700K (nosmt):

$ cat /sys/devices/system/cpu/cpu{0,8,16}/cpu_capacity
1009
1024
623

root@...liver:~# cat /sys/kernel/debug/energy_model/cpu0/ps:*/cost
6
7
8
9
root@...liver:~# cat /sys/kernel/debug/energy_model/cpu8/ps:*/cost
6
7
8
9
root@...liver:~# cat /sys/kernel/debug/energy_model/cpu16/ps:*/cost
4
5
6
7

Reviewed-by: Dietmar Eggemann <dietmar.eggemann@....com>