From: Daniel Lezcano <daniel.lezcano@linaro.org>
To: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>,
Sudeep Holla <sudeep.holla@arm.com>,
edubezval@gmail.com, kevin.wangtao@linaro.org,
leo.yan@linaro.org, vincent.guittot@linaro.org,
linux-kernel@vger.kernel.org, javi.merino@kernel.org,
rui.zhang@intel.com, daniel.thompson@linaro.org,
linux-pm@vger.kernel.org,
Amit Daniel Kachhap <amit.kachhap@gmail.com>
Subject: Re: [PATCH v3 6/7] thermal/drivers/cpu_cooling: Introduce the cpu idle cooling driver
Date: Mon, 16 Apr 2018 15:57:03 +0200 [thread overview]
Message-ID: <633cdc63-ce6d-89af-26dd-bdc3a27556ed@linaro.org> (raw)
In-Reply-To: <20180416123019.GA9341@e107981-ln.cambridge.arm.com>
On 16/04/2018 14:30, Lorenzo Pieralisi wrote:
> On Mon, Apr 16, 2018 at 02:10:30PM +0200, Daniel Lezcano wrote:
>> On 16/04/2018 12:10, Viresh Kumar wrote:
>>> On 16-04-18, 12:03, Daniel Lezcano wrote:
>>>> On 16/04/2018 11:50, Viresh Kumar wrote:
>>>>> On 16-04-18, 11:45, Daniel Lezcano wrote:
>>>>>> Can you elaborate a bit ? I'm not sure to get the point.
>>>>>
>>>>> Sure. With your current code on Hikey960 (big/LITTLE), you end up
>>>>> creating two cooling devices, one for the big cluster and one for
>>>>> small cluster. Which is the right thing to do, as we also have two
>>>>> cpufreq cooling devices.
>>>>>
>>>>> But with the change Sudeep is referring to, the helper you used to get
>>>>> cluster id will return 0 (SoC id) for all the 8 CPUs. So your code
>>>>> will end up creating a single cpuidle cooling device for all the CPUs.
>>>>> Which would be wrong.
>>>>
>>>> Is the semantic of topology_physical_package_id changing ?
>>>
>>> That's what I understood from his email.
>>>
>>>> I don't
>>>> understand the change Sudeep is referring to.
>>
>> Actually there is no impact with the change Sudeep is referring to. It
>> is for ACPI, we are DT based. Confirmed with Jeremy.
>>
>> So AFAICT, it is not a problem.
>
> It is a problem - DT or ACPI alike. Sudeep was referring to the notion
> of "cluster" that has no architectural meaning whatsoever and using
> topology_physical_package_id() to detect a "cluster" was/is/will always
> be the wrong thing to do. The notion of cluster must not appear in the
> kernel at all, it has no architectural meaning. I understand you need
> to group CPUs but that has to be done in a different way, through
> cooling devices, thermal domains or power domains DT/ACPI bindings but
> not by using topology masks.
I don't get it. What is the cluster concept defined in the ARM
documentation?
ARM Cortex-A53 MPCore Processor Technical Reference Manual
4.5.2. Multiprocessor Affinity Register
I see the documentation says:
A cluster with two cores, three cores, ...
How the kernel can represent that if you kill the
topology_physical_package_id() ?
> You should be able to figure out this week at OSPM the reasoning behind
> what I am saying above.
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next prev parent reply other threads:[~2018-04-16 13:57 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-05 16:16 [PATCH v3 0/7] CPU cooling device new strategies Daniel Lezcano
2018-04-05 16:16 ` [PATCH v3 1/7] thermal/drivers/cpu_cooling: Fixup the header and copyright Daniel Lezcano
[not found] ` <20180411061514.GL7671@vireshk-i7>
2018-04-11 8:56 ` Daniel Lezcano
2018-04-05 16:16 ` [PATCH v3 2/7] thermal/drivers/cpu_cooling: Add Software Package Data Exchange (SPDX) Daniel Lezcano
2018-04-05 16:16 ` [PATCH v3 3/7] thermal/drivers/cpu_cooling: Remove pointless field Daniel Lezcano
2018-04-05 16:16 ` [PATCH v3 4/7] thermal/drivers/Kconfig: Convert the CPU cooling device to a choice Daniel Lezcano
[not found] ` <20180411061851.GM7671@vireshk-i7>
2018-04-11 8:58 ` Daniel Lezcano
2018-04-05 16:16 ` [PATCH v3 5/7] thermal/drivers/cpu_cooling: Add idle cooling device documentation Daniel Lezcano
2018-04-05 16:16 ` [PATCH v3 6/7] thermal/drivers/cpu_cooling: Introduce the cpu idle cooling driver Daniel Lezcano
2018-04-11 8:51 ` Viresh Kumar
2018-04-11 9:29 ` Daniel Lezcano
2018-04-13 11:23 ` Sudeep Holla
2018-04-13 11:47 ` Daniel Lezcano
2018-04-16 7:37 ` Viresh Kumar
2018-04-16 7:44 ` Daniel Lezcano
2018-04-16 9:34 ` Sudeep Holla
2018-04-16 9:37 ` Viresh Kumar
2018-04-16 9:45 ` Daniel Lezcano
2018-04-16 9:50 ` Viresh Kumar
2018-04-16 10:03 ` Daniel Lezcano
2018-04-16 10:10 ` Viresh Kumar
2018-04-16 12:10 ` Daniel Lezcano
2018-04-16 12:30 ` Lorenzo Pieralisi
2018-04-16 13:57 ` Daniel Lezcano [this message]
2018-04-16 14:22 ` Lorenzo Pieralisi
2018-04-17 7:17 ` Daniel Lezcano
2018-04-17 10:24 ` Lorenzo Pieralisi
2018-04-16 12:31 ` Sudeep Holla
2018-04-16 12:49 ` Daniel Lezcano
2018-04-16 13:03 ` Sudeep Holla
2018-04-16 12:29 ` Sudeep Holla
2018-04-13 11:38 ` Daniel Thompson
2018-04-13 11:46 ` Daniel Lezcano
2019-08-05 5:11 ` Martin Kepplinger
2019-08-05 6:53 ` Martin Kepplinger
2019-08-05 7:39 ` Daniel Lezcano
2019-08-05 7:42 ` Martin Kepplinger
2019-08-05 7:58 ` Daniel Lezcano
2019-10-25 11:22 ` Martin Kepplinger
2019-10-25 14:45 ` Daniel Lezcano
2019-10-26 18:23 ` Martin Kepplinger
2019-10-28 15:16 ` Daniel Lezcano
2019-08-05 7:37 ` Daniel Lezcano
2019-08-05 7:40 ` Martin Kepplinger
2018-04-05 16:16 ` [PATCH v3 7/7] cpuidle/drivers/cpuidle-arm: Register the cooling device Daniel Lezcano
2018-04-11 8:51 ` Viresh Kumar
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