From: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> To: Ulf Hansson <ulf.hansson@linaro.org> Cc: Sudeep Holla <sudeep.holla@arm.com>, Mark Rutland <mark.rutland@arm.com>, Linux ARM <linux-arm-kernel@lists.infradead.org>, "Rafael J . Wysocki" <rjw@rjwysocki.net>, Daniel Lezcano <daniel.lezcano@linaro.org>, "Raju P . L . S . S . S . N" <rplsssn@codeaurora.org>, Amit Kucheria <amit.kucheria@linaro.org>, Bjorn Andersson <bjorn.andersson@linaro.org>, Stephen Boyd <sboyd@kernel.org>, Niklas Cassel <niklas.cassel@linaro.org>, Tony Lindgren <tony@atomide.com>, Kevin Hilman <khilman@kernel.org>, Lina Iyer <ilina@codeaurora.org>, Viresh Kumar <viresh.kumar@linaro.org>, Vincent Guittot <vincent.guittot@linaro.org>, Geert Uytterhoeven <geert+renesas@glider.be>, Souvik Chakravarty <souvik.chakravarty@arm.com>, Linux PM <linux-pm@vger.kernel.org>, linux-arm-msm <linux-arm-msm@vger.kernel.org>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org> Subject: Re: [PATCH 14/18] drivers: firmware: psci: Manage runtime PM in the idle path for CPUs Date: Thu, 18 Jul 2019 14:30:53 +0100 [thread overview] Message-ID: <20190718133053.GA27222@e121166-lin.cambridge.arm.com> (raw) In-Reply-To: <CAPDyKFrJ75mo+s6GuUCTQ-nVv7C+9YJyTVmwuBZ2RKFOvOi3Nw@mail.gmail.com> On Thu, Jul 18, 2019 at 12:35:07PM +0200, Ulf Hansson wrote: > On Tue, 16 Jul 2019 at 17:53, Lorenzo Pieralisi > <lorenzo.pieralisi@arm.com> wrote: > > > > On Mon, May 13, 2019 at 09:22:56PM +0200, Ulf Hansson wrote: > > > When the hierarchical CPU topology layout is used in DT, let's allow the > > > CPU to be power managed through its PM domain, via deploying runtime PM > > > support. > > > > > > To know for which idle states runtime PM reference counting is needed, > > > let's store the index of deepest idle state for the CPU, in a per CPU > > > variable. This allows psci_cpu_suspend_enter() to compare this index with > > > the requested idle state index and then act accordingly. > > > > I do not see why a system with two CPU CPUidle states, say CPU retention > > and CPU shutdown, should not be calling runtime PM on CPU retention > > entry. > > If the CPU idle governor did select the CPU retention for the CPU, it > was probably because the target residency for the CPU shutdown state > could not be met. The kernel does not know what those cpu states represent, so, this is an assumption you are making and it must be made clear that this code works as long as your assumption is valid. If eg a "cluster" retention state has lower target_residency than the deepest CPU idle state this assumption is wrong. And CPUidle and genPD governor decisions are not synced anyway so, again, this is an assumption, not a certainty. > In this case, there is no point in allowing any other deeper idle > states for cluster/package/system, since those have even greater > residencies, hence calling runtime PM doesn't make sense. On the systems you are testing on. Lorenzo > > The question then is what cluster/package/system states > > are allowed for a given CPU idle state, to understand > > what idle states can be actually entered at any hierarchy > > level given the choice made for the CPU idle state. > > > > In the case above, a CPU entering retention state should prevent > > runtime PM selecting a cluster shutdown state; most likely firmware > > would demote the request to cluster retention but still, we should > > find a way to describe these dependencies. > > See above. > > [...] > > Kind regards > Uffe
WARNING: multiple messages have this Message-ID (diff)
From: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> To: Ulf Hansson <ulf.hansson@linaro.org> Cc: Mark Rutland <mark.rutland@arm.com>, Geert Uytterhoeven <geert+renesas@glider.be>, Kevin Hilman <khilman@kernel.org>, Stephen Boyd <sboyd@kernel.org>, Viresh Kumar <viresh.kumar@linaro.org>, Linux PM <linux-pm@vger.kernel.org>, Daniel Lezcano <daniel.lezcano@linaro.org>, "Rafael J . Wysocki" <rjw@rjwysocki.net>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, Amit Kucheria <amit.kucheria@linaro.org>, Bjorn Andersson <bjorn.andersson@linaro.org>, Tony Lindgren <tony@atomide.com>, linux-arm-msm <linux-arm-msm@vger.kernel.org>, Lina Iyer <ilina@codeaurora.org>, Sudeep Holla <sudeep.holla@arm.com>, Niklas Cassel <niklas.cassel@linaro.org>, Souvik Chakravarty <souvik.chakravarty@arm.com>, "Raju P . L . S . S . S . N" <rplsssn@codeaurora.org>, Linux ARM <linux-arm-kernel@lists.infradead.org> Subject: Re: [PATCH 14/18] drivers: firmware: psci: Manage runtime PM in the idle path for CPUs Date: Thu, 18 Jul 2019 14:30:53 +0100 [thread overview] Message-ID: <20190718133053.GA27222@e121166-lin.cambridge.arm.com> (raw) In-Reply-To: <CAPDyKFrJ75mo+s6GuUCTQ-nVv7C+9YJyTVmwuBZ2RKFOvOi3Nw@mail.gmail.com> On Thu, Jul 18, 2019 at 12:35:07PM +0200, Ulf Hansson wrote: > On Tue, 16 Jul 2019 at 17:53, Lorenzo Pieralisi > <lorenzo.pieralisi@arm.com> wrote: > > > > On Mon, May 13, 2019 at 09:22:56PM +0200, Ulf Hansson wrote: > > > When the hierarchical CPU topology layout is used in DT, let's allow the > > > CPU to be power managed through its PM domain, via deploying runtime PM > > > support. > > > > > > To know for which idle states runtime PM reference counting is needed, > > > let's store the index of deepest idle state for the CPU, in a per CPU > > > variable. This allows psci_cpu_suspend_enter() to compare this index with > > > the requested idle state index and then act accordingly. > > > > I do not see why a system with two CPU CPUidle states, say CPU retention > > and CPU shutdown, should not be calling runtime PM on CPU retention > > entry. > > If the CPU idle governor did select the CPU retention for the CPU, it > was probably because the target residency for the CPU shutdown state > could not be met. The kernel does not know what those cpu states represent, so, this is an assumption you are making and it must be made clear that this code works as long as your assumption is valid. If eg a "cluster" retention state has lower target_residency than the deepest CPU idle state this assumption is wrong. And CPUidle and genPD governor decisions are not synced anyway so, again, this is an assumption, not a certainty. > In this case, there is no point in allowing any other deeper idle > states for cluster/package/system, since those have even greater > residencies, hence calling runtime PM doesn't make sense. On the systems you are testing on. Lorenzo > > The question then is what cluster/package/system states > > are allowed for a given CPU idle state, to understand > > what idle states can be actually entered at any hierarchy > > level given the choice made for the CPU idle state. > > > > In the case above, a CPU entering retention state should prevent > > runtime PM selecting a cluster shutdown state; most likely firmware > > would demote the request to cluster retention but still, we should > > find a way to describe these dependencies. > > See above. > > [...] > > Kind regards > Uffe _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2019-07-18 13:31 UTC|newest] Thread overview: 155+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-05-13 19:22 [PATCH 00/18] ARM/ARM64: Support hierarchical CPU arrangement for PSCI Ulf Hansson 2019-05-13 19:22 ` Ulf Hansson 2019-05-13 19:22 ` Ulf Hansson 2019-05-13 19:22 ` [PATCH 01/18] dt: psci: Update DT bindings to support hierarchical PSCI states Ulf Hansson 2019-05-13 19:22 ` Ulf Hansson 2019-05-13 19:22 ` Ulf Hansson 2019-07-19 11:29 ` Lorenzo Pieralisi 2019-07-19 11:29 ` Lorenzo Pieralisi 2019-05-13 19:22 ` [PATCH 02/18] of: base: Add of_get_cpu_state_node() to get idle states for a CPU node Ulf Hansson 2019-05-13 19:22 ` Ulf Hansson 2019-05-13 19:22 ` [PATCH 03/18] cpuidle: dt: Support hierarchical CPU idle states Ulf Hansson 2019-05-13 19:22 ` Ulf Hansson 2019-05-13 19:22 ` Ulf Hansson 2019-05-13 19:22 ` [PATCH 04/18] ARM/ARM64: cpuidle: Let back-end init ops take the driver as input Ulf Hansson 2019-05-13 19:22 ` Ulf Hansson 2019-05-13 19:22 ` Ulf Hansson 2019-06-07 15:00 ` Sudeep Holla 2019-06-07 15:00 ` Sudeep Holla 2019-06-10 10:20 ` Ulf Hansson 2019-06-10 10:20 ` Ulf Hansson 2019-05-13 19:22 ` [PATCH 05/18] drivers: firmware: psci: Simplify state node parsing Ulf Hansson 2019-05-13 19:22 ` Ulf Hansson 2019-05-13 19:22 ` Ulf Hansson 2019-06-07 15:01 ` Sudeep Holla 2019-06-07 15:01 ` Sudeep Holla 2019-05-13 19:22 ` [PATCH 06/18] drivers: firmware: psci: Support hierarchical CPU idle states Ulf Hansson 2019-05-13 19:22 ` Ulf Hansson 2019-05-13 19:22 ` Ulf Hansson 2019-06-07 15:03 ` Sudeep Holla 2019-06-07 15:03 ` Sudeep Holla 2019-05-13 19:22 ` [PATCH 07/18] drivers: firmware: psci: Prepare to use OS initiated suspend mode Ulf Hansson 2019-05-13 19:22 ` Ulf Hansson 2019-05-13 19:22 ` Ulf Hansson 2019-06-07 15:17 ` Sudeep Holla 2019-06-07 15:17 ` Sudeep Holla 2019-06-10 10:21 ` Ulf Hansson 2019-06-10 10:21 ` Ulf Hansson 2019-06-10 10:42 ` Sudeep Holla 2019-06-10 10:42 ` Sudeep Holla 2019-07-16 14:53 ` Sudeep Holla 2019-07-16 14:53 ` Sudeep Holla 2019-05-13 19:22 ` [PATCH 08/18] drivers: firmware: psci: Prepare to support PM domains Ulf Hansson 2019-05-13 19:22 ` Ulf Hansson 2019-05-13 19:22 ` Ulf Hansson 2019-06-07 15:21 ` Sudeep Holla 2019-06-07 15:21 ` Sudeep Holla 2019-05-13 19:22 ` [PATCH 09/18] drivers: firmware: psci: Add support for PM domains using genpd Ulf Hansson 2019-05-13 19:22 ` Ulf Hansson 2019-05-13 19:22 ` Ulf Hansson 2019-06-07 15:27 ` Sudeep Holla 2019-06-07 15:27 ` Sudeep Holla 2019-06-10 10:21 ` Ulf Hansson 2019-06-10 10:21 ` Ulf Hansson 2019-06-10 10:59 ` Sudeep Holla 2019-06-10 10:59 ` Sudeep Holla 2019-07-16 15:05 ` Sudeep Holla 2019-07-16 15:05 ` Sudeep Holla 2019-07-18 11:04 ` Ulf Hansson 2019-07-18 11:04 ` Ulf Hansson 2019-07-18 13:19 ` Sudeep Holla 2019-07-18 13:19 ` Sudeep Holla 2019-07-18 17:57 ` Lina Iyer 2019-07-18 17:57 ` Lina Iyer 2019-07-19 9:45 ` Sudeep Holla 2019-07-19 9:45 ` Sudeep Holla 2019-05-13 19:22 ` [PATCH 10/18] drivers: firmware: psci: Add hierarchical domain idle states converter Ulf Hansson 2019-05-13 19:22 ` Ulf Hansson 2019-05-13 19:22 ` Ulf Hansson 2019-07-09 15:31 ` Lorenzo Pieralisi 2019-07-09 15:31 ` Lorenzo Pieralisi 2019-07-16 8:45 ` Ulf Hansson 2019-07-16 8:45 ` Ulf Hansson 2019-07-16 14:51 ` Lorenzo Pieralisi 2019-07-16 14:51 ` Lorenzo Pieralisi 2019-07-18 11:43 ` Ulf Hansson 2019-07-18 11:43 ` Ulf Hansson 2019-07-18 13:36 ` Lorenzo Pieralisi 2019-07-18 13:36 ` Lorenzo Pieralisi 2019-05-13 19:22 ` [PATCH 11/18] drivers: firmware: psci: Introduce psci_dt_topology_init() Ulf Hansson 2019-05-13 19:22 ` Ulf Hansson 2019-05-13 19:22 ` [PATCH 12/18] drivers: firmware: psci: Add a helper to attach a CPU to its PM domain Ulf Hansson 2019-05-13 19:22 ` Ulf Hansson 2019-05-13 19:22 ` Ulf Hansson 2019-05-13 19:22 ` [PATCH 13/18] drivers: firmware: psci: Attach the CPU's device " Ulf Hansson 2019-05-13 19:22 ` Ulf Hansson 2019-05-13 19:22 ` Ulf Hansson 2019-05-13 19:22 ` [PATCH 14/18] drivers: firmware: psci: Manage runtime PM in the idle path for CPUs Ulf Hansson 2019-05-13 19:22 ` Ulf Hansson 2019-05-13 19:22 ` Ulf Hansson 2019-07-16 15:53 ` Lorenzo Pieralisi 2019-07-16 15:53 ` Lorenzo Pieralisi 2019-07-18 10:35 ` Ulf Hansson 2019-07-18 10:35 ` Ulf Hansson 2019-07-18 13:30 ` Lorenzo Pieralisi [this message] 2019-07-18 13:30 ` Lorenzo Pieralisi 2019-07-18 16:54 ` Ulf Hansson 2019-07-18 16:54 ` Ulf Hansson 2019-07-18 17:41 ` Lina Iyer 2019-07-18 17:41 ` Lina Iyer 2019-07-18 21:49 ` Ulf Hansson 2019-07-18 21:49 ` Ulf Hansson 2019-07-19 10:02 ` Lorenzo Pieralisi 2019-07-19 10:02 ` Lorenzo Pieralisi 2019-05-13 19:22 ` [PATCH 15/18] drivers: firmware: psci: Support CPU hotplug for the hierarchical model Ulf Hansson 2019-05-13 19:22 ` Ulf Hansson 2019-05-13 19:22 ` Ulf Hansson 2019-06-07 15:31 ` Sudeep Holla 2019-06-07 15:31 ` Sudeep Holla 2019-06-10 10:21 ` Ulf Hansson 2019-06-10 10:21 ` Ulf Hansson 2019-06-10 11:02 ` Sudeep Holla 2019-06-10 11:02 ` Sudeep Holla 2019-05-13 19:22 ` [PATCH 16/18] arm64: kernel: Respect the hierarchical CPU topology in DT for PSCI Ulf Hansson 2019-05-13 19:22 ` Ulf Hansson 2019-05-13 19:22 ` Ulf Hansson 2019-05-13 19:22 ` [PATCH 17/18] arm64: dts: Convert to the hierarchical CPU topology layout for MSM8916 Ulf Hansson 2019-05-13 19:22 ` Ulf Hansson 2019-05-13 19:22 ` Ulf Hansson 2019-07-16 14:47 ` Sudeep Holla 2019-07-16 14:47 ` Sudeep Holla 2019-07-16 20:36 ` Lina Iyer 2019-07-16 20:36 ` Lina Iyer 2019-07-17 17:18 ` Sudeep Holla 2019-07-17 17:18 ` Sudeep Holla 2019-05-13 19:23 ` [PATCH 18/18] arm64: dts: hikey: Convert to the hierarchical CPU topology layout Ulf Hansson 2019-05-13 19:23 ` Ulf Hansson 2019-05-13 19:23 ` Ulf Hansson 2019-07-16 14:47 ` Sudeep Holla 2019-07-16 14:47 ` Sudeep Holla 2019-07-18 10:48 ` Ulf Hansson 2019-07-18 10:48 ` Ulf Hansson 2019-07-18 13:11 ` Sudeep Holla 2019-07-18 13:11 ` Sudeep Holla 2019-05-14 8:08 ` [PATCH 00/18] ARM/ARM64: Support hierarchical CPU arrangement for PSCI Rafael J. Wysocki 2019-05-14 8:08 ` Rafael J. Wysocki 2019-05-14 8:08 ` Rafael J. Wysocki 2019-05-14 8:58 ` Ulf Hansson 2019-05-14 8:58 ` Ulf Hansson 2019-05-14 8:58 ` Ulf Hansson 2019-06-07 15:42 ` Sudeep Holla 2019-06-07 15:42 ` Sudeep Holla 2019-06-07 19:34 ` Bjorn Andersson 2019-06-07 19:34 ` Bjorn Andersson 2019-06-10 10:32 ` Sudeep Holla 2019-06-10 10:32 ` Sudeep Holla 2019-06-10 15:54 ` Ulf Hansson 2019-06-10 15:54 ` Ulf Hansson 2019-06-10 17:16 ` Lorenzo Pieralisi 2019-06-10 17:16 ` Lorenzo Pieralisi 2019-06-10 18:57 ` Ulf Hansson 2019-06-10 18:57 ` Ulf Hansson 2019-06-18 11:56 ` Ulf Hansson 2019-06-18 11:56 ` Ulf Hansson 2019-06-07 11:19 ` Ulf Hansson 2019-06-07 11:19 ` Ulf Hansson
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