On 6 August 2018 at 11:36, Rafael J. Wysocki <rafael@xxxxxxxxxx> wrote:
> On Fri, Aug 3, 2018 at 1:43 PM, Ulf Hansson <ulf.hansson@xxxxxxxxxx> wrote:
>> On 19 July 2018 at 12:25, Rafael J. Wysocki <rjw@xxxxxxxxxxxxx> 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@xxxxxxxxxxxxxx>
>>>> Co-developed-by: Lina Iyer <lina.iyer@xxxxxxxxxx>
>>>> Signed-off-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
>>>> ---
>>>> 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
