From: k.kozlowski@samsung•com (Krzysztof Kozlowski)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH RFC 3/3] PM / Domains: Introduce generic PM domain for cpu domain
Date: Thu, 11 Jun 2015 09:35:44 +0900 [thread overview]
Message-ID: <5578D7E0.8020305@samsung.com> (raw)
In-Reply-To: <7hbngnpkfd.fsf@deeprootsystems.com>
On 11.06.2015 02:01, Kevin Hilman wrote:
> Krzysztof Kozlowski <k.kozlowski@samsung•com> writes:
>
>> W dniu 05.06.2015 o 07:29, Lina Iyer pisze:
>>> Generally cpus are grouped under a power domain in a SoC. When all cpus
>>> in the domain are in their power off state,
>>
>> What do you exactly mean here by "CPU in power off state"? How does it
>> map to kernel understanding of CPU device (hotplug? cpuidle?)?
>>
>>> the cpu domain can also be
>>> powered off. Genpd provides the framework for defining cpus as devices
>>> that are part of a cpu domain.
>>
>> The problem which is solved looks to me like the same problem which
>> coupled cpuidle tried to solve: a certain deep sleep mode (e.g. power
>> off) can be entered when whole cluster is idle or other CPUs in cluster
>> are powered off completely.
>>
>> It seems a little like duplicating the effort around coupled cpuidle.
>
> Yes, it duplicates some aspects of coupled idle states, but coupled
> states have their own limitations:
>
> - only handles CPUs, not other devices sharing a power rail (e.g. L2$,
> GIC, floating point unit, CoreSight, etc. etc.)
>
> - not scaling well past 2 CPUs
>
> - doesn't handle clusters: While this series only addresses CPUs
> currently, the approach can be extended. Because genpd handles nested
> domains, the could be used to model clusters as well.
Right. I agree with your explanation. I am just thinking how to utilize
this for Exynos deep sleep modes which now we implement using coupled
cpuidle.
Anyway I like the idea!
Best regards,
Krzysztof
next prev parent reply other threads:[~2015-06-11 0:35 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-04 22:29 [PATCH RFC 0/3] PM / Domains: Generic PM domains for cpus Lina Iyer
2015-06-04 22:29 ` [PATCH RFC 1/3] PM / Domains: Allocate memory outside domain locks Lina Iyer
2015-06-07 8:35 ` Krzysztof Kozlowski
2015-06-09 22:45 ` Lina Iyer
2015-06-10 17:33 ` Kevin Hilman
2015-06-04 22:29 ` [PATCH RFC 2/3] PM / Domains: Support atomic PM domains Lina Iyer
2015-06-07 9:21 ` Krzysztof Kozlowski
2015-06-10 16:13 ` Lina Iyer
2015-06-11 0:13 ` Krzysztof Kozlowski
2015-06-11 14:33 ` Lina Iyer
2015-06-10 18:04 ` Kevin Hilman
2015-06-10 20:35 ` Lina Iyer
2015-06-11 9:41 ` Ulf Hansson
2015-06-11 19:47 ` Lina Iyer
2015-06-11 21:13 ` Ulf Hansson
2015-06-04 22:29 ` [PATCH RFC 3/3] PM / Domains: Introduce generic PM domain for cpu domain Lina Iyer
2015-06-07 9:42 ` Krzysztof Kozlowski
2015-06-10 16:57 ` Lina Iyer
2015-06-11 0:27 ` Krzysztof Kozlowski
2015-06-11 14:42 ` Lina Iyer
2015-06-10 17:01 ` Kevin Hilman
2015-06-11 0:35 ` Krzysztof Kozlowski [this message]
2015-06-10 21:37 ` Kevin Hilman
2015-06-11 14:56 ` Lina Iyer
2015-06-15 18:43 ` Kevin Hilman
2015-06-15 19:14 ` Lina Iyer
2015-06-16 15:50 ` Kevin Hilman
2015-06-10 17:24 ` [PATCH RFC 0/3] PM / Domains: Generic PM domains for cpus Kevin Hilman
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