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From: Ulf Hansson <ulf.hansson@linaro.org>
To: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>,
	Sudeep Holla <sudeep.holla@arm.com>,
	Lorenzo Pieralisi <Lorenzo.Pieralisi@arm.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Linux PM <linux-pm@vger.kernel.org>,
	Kevin Hilman <khilman@kernel.org>,
	Lina Iyer <ilina@codeaurora.org>,
	Lina Iyer <lina.iyer@linaro.org>,
	Rob Herring <robh+dt@kernel.org>,
	Daniel Lezcano <daniel.lezcano@linaro.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Stephen Boyd <sboyd@kernel.org>, Juri Lelli <juri.lelli@arm.com>,
	Geert Uytterhoeven <geert+renesas@glider.be>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>,
	linux-arm-msm <linux-arm-msm@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v8 04/26] PM / Domains: Add support for CPU devices to genpd
Date: Fri, 24 Aug 2018 08:47:21 +0200	[thread overview]
Message-ID: <CAPDyKFpatx81aMrbDtaeNPH=FXBYPCHsog3i=a0VN5=Q8if0=Q@mail.gmail.com> (raw)
In-Reply-To: <CAJZ5v0jah=aiYoV_b_p=-x+puO0sxeGRBCtJnQAD8xb8p1QGfg@mail.gmail.com>

On 6 August 2018 at 11:36, Rafael J. Wysocki <rafael@kernel.org> wrote:
> On Fri, Aug 3, 2018 at 1:43 PM, Ulf Hansson <ulf.hansson@linaro.org> wrote:
>> On 19 July 2018 at 12:25, Rafael J. Wysocki <rjw@rjwysocki.net> wrote:
>>> On Wednesday, June 20, 2018 7:22:04 PM CEST Ulf Hansson wrote:
>>>> To enable a device belonging to a CPU to be attached to a PM domain managed
>>>> by genpd, let's do a few changes to genpd as to make it convenient to
>>>> manage the specifics around CPUs.
>>>>
>>>> First, as to be able to quickly find out what CPUs that are attached to a
>>>> genpd, which typically becomes useful from a genpd governor as following
>>>> changes is about to show, let's add a cpumask 'cpus' to the struct
>>>> generic_pm_domain.
>>>>
>>>> At the point when a device that belongs to a CPU, is attached/detached to
>>>> its corresponding PM domain via genpd_add_device(), let's update the
>>>> cpumask in genpd->cpus. Moreover, propagate the update of the cpumask to
>>>> the master domains, which makes the genpd->cpus to contain a cpumask that
>>>> hierarchically reflect all CPUs for a genpd, including CPUs attached to
>>>> subdomains.
>>>>
>>>> Second, to unconditionally manage CPUs and the cpumask in genpd->cpus, is
>>>> unnecessary for cases when only non-CPU devices are parts of a genpd.
>>>> Let's avoid this by adding a new configuration bit, GENPD_FLAG_CPU_DOMAIN.
>>>> Clients must set the bit before they call pm_genpd_init(), as to instruct
>>>> genpd that it shall deal with CPUs and thus manage the cpumask in
>>>> genpd->cpus.
>>>>
>>>> Cc: Lina Iyer <ilina@codeaurora.org>
>>>> Co-developed-by: Lina Iyer <lina.iyer@linaro.org>
>>>> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
>>>> ---
>>>>  drivers/base/power/domain.c | 69 ++++++++++++++++++++++++++++++++++++-
>>>>  include/linux/pm_domain.h   |  3 ++
>>>>  2 files changed, 71 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
>>>> index 21d298e1820b..6149ce0bfa7b 100644
>>>> --- a/drivers/base/power/domain.c
>>>> +++ b/drivers/base/power/domain.c
>>>> @@ -20,6 +20,7 @@
>>>>  #include <linux/sched.h>
>>>>  #include <linux/suspend.h>
>>>>  #include <linux/export.h>
>>>> +#include <linux/cpu.h>
>>>>
>>>>  #include "power.h"
>>>>
>>>> @@ -126,6 +127,7 @@ static const struct genpd_lock_ops genpd_spin_ops = {
>>>>  #define genpd_is_irq_safe(genpd)     (genpd->flags & GENPD_FLAG_IRQ_SAFE)
>>>>  #define genpd_is_always_on(genpd)    (genpd->flags & GENPD_FLAG_ALWAYS_ON)
>>>>  #define genpd_is_active_wakeup(genpd)        (genpd->flags & GENPD_FLAG_ACTIVE_WAKEUP)
>>>> +#define genpd_is_cpu_domain(genpd)   (genpd->flags & GENPD_FLAG_CPU_DOMAIN)
>>>>
>>>>  static inline bool irq_safe_dev_in_no_sleep_domain(struct device *dev,
>>>>               const struct generic_pm_domain *genpd)
>>>> @@ -1377,6 +1379,62 @@ static void genpd_free_dev_data(struct device *dev,
>>>>       dev_pm_put_subsys_data(dev);
>>>>  }
>>>>
>>>> +static void __genpd_update_cpumask(struct generic_pm_domain *genpd,
>>>> +                                int cpu, bool set, unsigned int depth)
>>>> +{
>>>> +     struct gpd_link *link;
>>>> +
>>>> +     if (!genpd_is_cpu_domain(genpd))
>>>> +             return;
>>>> +
>>>> +     list_for_each_entry(link, &genpd->slave_links, slave_node) {
>>>> +             struct generic_pm_domain *master = link->master;
>>>> +
>>>> +             genpd_lock_nested(master, depth + 1);
>>>> +             __genpd_update_cpumask(master, cpu, set, depth + 1);
>>>> +             genpd_unlock(master);
>>>> +     }
>>>> +
>>>> +     if (set)
>>>> +             cpumask_set_cpu(cpu, genpd->cpus);
>>>> +     else
>>>> +             cpumask_clear_cpu(cpu, genpd->cpus);
>>>> +}
>>>
>>> As noted elsewhere, there is a concern about the possible weight of this
>>> cpumask and I think that it would be good to explicitly put a limit on it.
>>
>> I have been digesting your comments on the series, but wonder if this
>> is still a relevant concern?
>
> Well, there are systems with very large cpumasks and it is sort of
> good to have that in mind when designing any code using them.

Right.

So, if I avoid allocating the cpumask for those genpd structures that
doesn't need it (those not having GENPD_FLAG_CPU_DOMAIN set), would
that be sufficient to deal with your concern?

Kind regards
Uffe

  reply	other threads:[~2018-08-24  6:47 UTC|newest]

Thread overview: 74+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-06-20 17:22 [PATCH v8 00/26] PM / Domains: Support hierarchical CPU arrangement (PSCI/ARM) Ulf Hansson
2018-06-20 17:22 ` [PATCH v8 01/26] PM / Domains: Don't treat zero found compatible idle states as an error Ulf Hansson
2018-06-20 17:22 ` [PATCH v8 02/26] PM / Domains: Deal with multiple states but no governor in genpd Ulf Hansson
2018-06-20 17:22 ` [PATCH v8 03/26] PM / Domains: Add generic data pointer to genpd_power_state struct Ulf Hansson
2018-06-24 21:09   ` Rafael J. Wysocki
2018-06-25  8:34     ` Ulf Hansson
2018-06-20 17:22 ` [PATCH v8 04/26] PM / Domains: Add support for CPU devices to genpd Ulf Hansson
2018-07-19 10:25   ` Rafael J. Wysocki
2018-08-03 11:43     ` Ulf Hansson
2018-08-06  9:36       ` Rafael J. Wysocki
2018-08-24  6:47         ` Ulf Hansson [this message]
2018-09-14  9:26           ` Rafael J. Wysocki
2018-06-20 17:22 ` [PATCH v8 05/26] PM / Domains: Add helper functions to attach/detach CPUs to/from genpd Ulf Hansson
2018-07-19 10:22   ` Rafael J. Wysocki
2018-08-03 11:44     ` Ulf Hansson
2018-06-20 17:22 ` [PATCH v8 06/26] timer: Export next wakeup time of a CPU Ulf Hansson
2018-07-19 10:15   ` Rafael J. Wysocki
2018-06-20 17:22 ` [PATCH v8 07/26] PM / Domains: Add genpd governor for CPUs Ulf Hansson
2018-07-19 10:32   ` Rafael J. Wysocki
2018-07-26  9:14     ` Rafael J. Wysocki
2018-08-03 14:28       ` Ulf Hansson
2018-08-06  9:20         ` Rafael J. Wysocki
2018-08-09 15:39           ` Lorenzo Pieralisi
2018-08-24  9:26             ` Ulf Hansson
2018-08-24 10:38               ` Lorenzo Pieralisi
2018-08-30 13:36                 ` Ulf Hansson
2018-09-13 15:37                   ` Lorenzo Pieralisi
2018-09-14  9:50             ` Rafael J. Wysocki
2018-09-14 10:44               ` Lorenzo Pieralisi
2018-09-14 11:34                 ` Rafael J. Wysocki
2018-09-14 12:30                   ` Lorenzo Pieralisi
2018-08-24  8:29           ` Ulf Hansson
2018-06-20 17:22 ` [PATCH v8 08/26] PM / Domains: Extend genpd CPU governor to cope with QoS constraints Ulf Hansson
2018-07-19 10:35   ` Rafael J. Wysocki
2018-08-03 11:42     ` Ulf Hansson
2018-06-20 17:22 ` [PATCH v8 09/26] kernel/cpu_pm: Manage runtime PM in the idle path for CPUs Ulf Hansson
2018-07-18 10:11   ` Rafael J. Wysocki
2018-07-19 10:12     ` Rafael J. Wysocki
2018-07-19 10:39       ` Rafael J. Wysocki
2018-08-03 11:42         ` Ulf Hansson
2018-08-06  9:37           ` Rafael J. Wysocki
2018-08-08 10:56             ` Lorenzo Pieralisi
2018-08-08 18:02               ` Lina Iyer
2018-08-09  8:16                 ` Rafael J. Wysocki
2018-08-10 20:36                   ` Lina Iyer
2018-08-12  9:53                     ` Rafael J. Wysocki
2018-08-09  9:58                 ` Sudeep Holla
2018-08-09 10:25                 ` Lorenzo Pieralisi
2018-08-10 20:18                   ` Lina Iyer
2018-08-15 10:44                     ` Lorenzo Pieralisi
2018-08-24 12:24                       ` Ulf Hansson
2018-06-20 17:22 ` [PATCH v8 10/26] dt: psci: Update DT bindings to support hierarchical PSCI states Ulf Hansson
2018-06-20 17:22 ` [PATCH v8 11/26] of: base: Add of_get_cpu_state_node() to get idle states for a CPU node Ulf Hansson
2018-06-20 17:22 ` [PATCH v8 12/26] cpuidle: dt: Support hierarchical CPU idle states Ulf Hansson
2018-06-20 17:22 ` [PATCH v8 13/26] drivers: firmware: psci: Move psci to separate directory Ulf Hansson
2018-06-20 17:22 ` [PATCH v8 14/26] MAINTAINERS: Update files for PSCI Ulf Hansson
2018-06-20 17:22 ` [PATCH v8 15/26] drivers: firmware: psci: Split psci_dt_cpu_init_idle() Ulf Hansson
2018-06-20 17:22 ` [PATCH v8 16/26] drivers: firmware: psci: Support hierarchical CPU idle states Ulf Hansson
2018-06-20 17:22 ` [PATCH v8 17/26] drivers: firmware: psci: Simplify error path of psci_dt_init() Ulf Hansson
2018-06-20 17:22 ` [PATCH v8 18/26] drivers: firmware: psci: Announce support for OS initiated suspend mode Ulf Hansson
2018-06-20 17:22 ` [PATCH v8 19/26] drivers: firmware: psci: Prepare to use " Ulf Hansson
2018-06-20 17:22 ` [PATCH v8 20/26] drivers: firmware: psci: Share a few internal PSCI functions Ulf Hansson
2018-06-20 17:22 ` [PATCH v8 21/26] drivers: firmware: psci: Add support for PM domains using genpd Ulf Hansson
2018-06-20 17:22 ` [PATCH v8 22/26] drivers: firmware: psci: Introduce psci_dt_topology_init() Ulf Hansson
2018-06-20 17:22 ` [PATCH v8 23/26] drivers: firmware: psci: Try to attach CPU devices to their PM domains Ulf Hansson
2018-06-20 17:22 ` [PATCH v8 24/26] drivers: firmware: psci: Deal with CPU hotplug when using OSI mode Ulf Hansson
2018-11-19 19:50   ` Raju P L S S S N
2018-11-20  9:50     ` Ulf Hansson
2018-11-20 10:47       ` Raju P L S S S N
2018-06-20 17:22 ` [PATCH v8 25/26] arm64: kernel: Respect the hierarchical CPU topology in DT for PSCI Ulf Hansson
2018-06-20 17:22 ` [PATCH v8 26/26] arm64: dts: Convert to the hierarchical CPU topology layout for MSM8916 Ulf Hansson
2018-07-03  5:44 ` [PATCH v8 00/26] PM / Domains: Support hierarchical CPU arrangement (PSCI/ARM) Ulf Hansson
2018-07-03  7:54   ` Rafael J. Wysocki
2018-07-09 11:42     ` Ulf Hansson

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