linux-kernel - Re: [PATCH 0/5] Rework system pressure interface to the scheduler

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Message-ID: <2b0524b9-3b54-4548-9054-2ba48eed6b65@arm.com>
Date: Fri, 15 Dec 2023 15:54:13 +0000
From: Lukasz Luba <lukasz.luba@....com>
To: Vincent Guittot <vincent.guittot@...aro.org>
Cc: catalin.marinas@....com, will@...nel.org,
 linux-trace-kernel@...r.kernel.org, amit.kachhap@...il.com,
 daniel.lezcano@...aro.org, mhiramat@...nel.org, vschneid@...hat.com,
 bristot@...hat.com, mgorman@...e.de, bsegall@...gle.com,
 juri.lelli@...hat.com, peterz@...radead.org, mingo@...hat.com,
 linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
 konrad.dybcio@...aro.org, andersson@...nel.org, agross@...nel.org,
 rui.zhang@...el.com, viresh.kumar@...aro.org, rafael@...nel.org,
 sudeep.holla@....com, dietmar.eggemann@....com, rostedt@...dmis.org,
 linux-arm-kernel@...ts.infradead.org, linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH 0/5] Rework system pressure interface to the scheduler



On 12/14/23 08:32, Lukasz Luba wrote:
> 
> 
> On 12/14/23 08:29, Vincent Guittot wrote:
>> On Thu, 14 Dec 2023 at 09:21, Lukasz Luba <lukasz.luba@....com> wrote:
>>>
>>> Hi Vincent,
>>>
>>> I've been waiting for this feature, thanks!
>>>
>>>
>>> On 12/12/23 14:27, Vincent Guittot wrote:
>>>> Following the consolidation and cleanup of CPU capacity in [1], this 
>>>> serie
>>>> reworks how the scheduler gets the pressures on CPUs. We need to 
>>>> take into
>>>> account all pressures applied by cpufreq on the compute capacity of 
>>>> a CPU
>>>> for dozens of ms or more and not only cpufreq cooling device or HW
>>>> mitigiations. we split the pressure applied on CPU's capacity in 2 
>>>> parts:
>>>> - one from cpufreq and freq_qos
>>>> - one from HW high freq mitigiation.
>>>>
>>>> The next step will be to add a dedicated interface for long standing
>>>> capping of the CPU capacity (i.e. for seconds or more) like the
>>>> scaling_max_freq of cpufreq sysfs. The latter is already taken into
>>>> account by this serie but as a temporary pressure which is not 
>>>> always the
>>>> best choice when we know that it will happen for seconds or more.
>>>>
>>>> [1] 
>>>> https://lore.kernel.org/lkml/20231211104855.558096-1-vincent.guittot@linaro.org/
>>>>
>>>> Vincent Guittot (4):
>>>>     cpufreq: Add a cpufreq pressure feedback for the scheduler
>>>>     sched: Take cpufreq feedback into account
>>>>     thermal/cpufreq: Remove arch_update_thermal_pressure()
>>>>     sched: Rename arch_update_thermal_pressure into
>>>>       arch_update_hw_pressure
>>>>
>>>>    arch/arm/include/asm/topology.h               |  6 +--
>>>>    arch/arm64/include/asm/topology.h             |  6 +--
>>>>    drivers/base/arch_topology.c                  | 26 ++++-----
>>>>    drivers/cpufreq/cpufreq.c                     | 48 +++++++++++++++++
>>>>    drivers/cpufreq/qcom-cpufreq-hw.c             |  4 +-
>>>>    drivers/thermal/cpufreq_cooling.c             |  3 --
>>>>    include/linux/arch_topology.h                 |  8 +--
>>>>    include/linux/cpufreq.h                       | 10 ++++
>>>>    include/linux/sched/topology.h                |  8 +--
>>>>    .../{thermal_pressure.h => hw_pressure.h}     | 14 ++---
>>>>    include/trace/events/sched.h                  |  2 +-
>>>>    init/Kconfig                                  | 12 ++---
>>>>    kernel/sched/core.c                           |  8 +--
>>>>    kernel/sched/fair.c                           | 53 
>>>> ++++++++++---------
>>>>    kernel/sched/pelt.c                           | 18 +++----
>>>>    kernel/sched/pelt.h                           | 16 +++---
>>>>    kernel/sched/sched.h                          |  4 +-
>>>>    17 files changed, 152 insertions(+), 94 deletions(-)
>>>>    rename include/trace/events/{thermal_pressure.h => hw_pressure.h} 
>>>> (55%)
>>>>
>>>
>>> I would like to test it, but something worries me. Why there is 0/5 in
>>> this subject and only 4 patches?
>>
>> I removed a patch from the series but copied/pasted the cover letter
>> subject without noticing the /5 instead of /4
> 
> OK
> 
>>
>>>
>>> Could you tell me your base branch that I can apply this, please?
>>
>> It applies on top of tip/sched/core + [1]
>> and you can find it here:
>> https://git.linaro.org/people/vincent.guittot/kernel.git/log/?h=sched/system-pressure
> 
> Thanks for the info and handy link.
> 

I've tested your patches with: DTPM/PowerCap + thermal gov + cpufreq
sysfs scaling_max_freq. It works fine all my cases (couldn't cause
any issues). If you like to test DTPM you will need 2 fixed pending
in Rafael's tree.

So, I'm looking for a your v2 to continue reviewing it.