From: Amit Kucheria <amit.kucheria@verdurent.com>
To: Thara Gopinath <thara.gopinath@linaro.org>
Cc: Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
ionela.voinescu@arm.com,
Vincent Guittot <vincent.guittot@linaro.org>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Zhang Rui <rui.zhang@intel.com>,
qperret@google.com, Daniel Lezcano <daniel.lezcano@linaro.org>,
Viresh Kumar <viresh.kumar@linaro.org>,
Steven Rostedt <rostedt@goodmis.org>,
Will Deacon <will@kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Sudeep Holla <sudeep.holla@arm.com>,
Juri Lelli <juri.lelli@redhat.com>,
corbet@lwn.net, LKML <linux-kernel@vger.kernel.org>,
Amit Daniel Kachhap <amit.kachhap@gmail.com>,
Javi Merino <javi.merino@kernel.org>
Subject: Re: [Patch v9 3/8] arm,arm64,drivers:Add infrastructure to store and update instantaneous thermal pressure
Date: Thu, 13 Feb 2020 17:55:47 +0530 [thread overview]
Message-ID: <CAHLCerMEieWMyk8RcM-y8c3Usq_e5CTYJ4AqhCQOzihRTUWbTg@mail.gmail.com> (raw)
In-Reply-To: <1580250967-4386-4-git-send-email-thara.gopinath@linaro.org>
On Wed, Jan 29, 2020 at 4:06 AM Thara Gopinath
<thara.gopinath@linaro.org> wrote:
>
> Add architecture specific APIs to update and track thermal pressure on a
> per cpu basis. A per cpu variable thermal_pressure is introduced to keep
> track of instantaneous per cpu thermal pressure. Thermal pressure is the
> delta between maximum capacity and capped capacity due to a thermal event.
s/capped/decreased to have consistent use throughout the series e.g. in patch 1.
Though personally, I like "capped capacity" in which case
s/decreased/capped in patch 1 and elsewhere.
>
> topology_get_thermal_pressure can be hooked into the scheduler specified
> arch_cpu_thermal_capacity to retrieve instantaneous thermal pressure of a
> cpu.
>
> arch_set_thermal_pressure can be used to update the thermal pressure.
>
> Considering topology_get_thermal_pressure reads thermal_pressure and
> arch_set_thermal_pressure writes into thermal_pressure, one can argue for
> some sort of locking mechanism to avoid a stale value. But considering
> topology_get_thermal_pressure can be called from a system critical path
> like scheduler tick function, a locking mechanism is not ideal. This means
> that it is possible the thermal_pressure value used to calculate average
> thermal pressure for a cpu can be stale for upto 1 tick period.
>
> Signed-off-by: Thara Gopinath <thara.gopinath@linaro.org>
> ---
>
> v6->v7:
> - Changed the input argument in arch_set_thermal_pressure from
> capped capacity to delta capacity(thermal pressure) as per
> Ionela's review comments.
>
> arch/arm/include/asm/topology.h | 3 +++
> arch/arm64/include/asm/topology.h | 3 +++
Any particular reason to enable this for arm/arm64 in this patch
itself? I'd have enabled them in two separate patches after this one.
> drivers/base/arch_topology.c | 11 +++++++++++
> include/linux/arch_topology.h | 10 ++++++++++
> 4 files changed, 27 insertions(+)
>
> diff --git a/arch/arm/include/asm/topology.h b/arch/arm/include/asm/topology.h
> index 8a0fae9..3a50a19 100644
> --- a/arch/arm/include/asm/topology.h
> +++ b/arch/arm/include/asm/topology.h
> @@ -16,6 +16,9 @@
> /* Enable topology flag updates */
> #define arch_update_cpu_topology topology_update_cpu_topology
>
> +/* Replace task scheduler's default thermal pressure retrieve API */
> +#define arch_cpu_thermal_pressure topology_get_thermal_pressure
> +
> #else
>
> static inline void init_cpu_topology(void) { }
> diff --git a/arch/arm64/include/asm/topology.h b/arch/arm64/include/asm/topology.h
> index a4d945d..a70896f 100644
> --- a/arch/arm64/include/asm/topology.h
> +++ b/arch/arm64/include/asm/topology.h
> @@ -25,6 +25,9 @@ int pcibus_to_node(struct pci_bus *bus);
> /* Enable topology flag updates */
> #define arch_update_cpu_topology topology_update_cpu_topology
>
> +/* Replace task scheduler's default thermal pressure retrieve API */
> +#define arch_cpu_thermal_pressure topology_get_thermal_pressure
> +
> #include <asm-generic/topology.h>
>
> #endif /* _ASM_ARM_TOPOLOGY_H */
> diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c
> index 6119e11..68dfa49 100644
> --- a/drivers/base/arch_topology.c
> +++ b/drivers/base/arch_topology.c
> @@ -42,6 +42,17 @@ void topology_set_cpu_scale(unsigned int cpu, unsigned long capacity)
> per_cpu(cpu_scale, cpu) = capacity;
> }
>
> +DEFINE_PER_CPU(unsigned long, thermal_pressure);
> +
> +void arch_set_thermal_pressure(struct cpumask *cpus,
> + unsigned long th_pressure)
> +{
> + int cpu;
<snip>
next prev parent reply other threads:[~2020-02-13 12:26 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-28 22:35 [Patch v9 0/8] Introduce Thermal Pressure Thara Gopinath
2020-01-28 22:36 ` [Patch v9 1/8] sched/pelt: Add support to track thermal pressure Thara Gopinath
2020-02-13 12:29 ` Amit Kucheria
2020-02-13 14:11 ` Thara Gopinath
2020-02-13 14:41 ` Amit Kucheria
2020-01-28 22:36 ` [Patch v9 2/8] sched/topology: Add hook to read per cpu " Thara Gopinath
2020-01-28 22:36 ` [Patch v9 3/8] arm,arm64,drivers:Add infrastructure to store and update instantaneous " Thara Gopinath
2020-02-13 12:25 ` Amit Kucheria [this message]
2020-02-13 14:05 ` Thara Gopinath
2020-02-13 14:38 ` Amit Kucheria
2020-02-14 15:01 ` Thara Gopinath
2020-01-28 22:36 ` [Patch v9 4/8] sched/fair: Enable periodic update of average " Thara Gopinath
2020-01-28 22:36 ` [Patch v9 5/8] sched/fair: update cpu_capacity to reflect " Thara Gopinath
2020-02-13 12:47 ` Amit Kucheria
2020-02-13 14:12 ` Thara Gopinath
2020-02-13 13:39 ` Amit Kucheria
2020-02-14 14:52 ` Thara Gopinath
2020-01-28 22:36 ` [Patch v9 6/8] thermal/cpu-cooling: Update thermal pressure in case of a maximum frequency capping Thara Gopinath
2020-01-28 22:36 ` [Patch v9 7/8] sched/fair: Enable tuning of decay period Thara Gopinath
2020-01-28 23:56 ` Randy Dunlap
2020-02-03 12:07 ` Thara Gopinath
2020-02-03 15:55 ` Peter Zijlstra
2020-02-04 8:39 ` Dietmar Eggemann
2020-02-07 22:42 ` Thara Gopinath
2020-02-10 11:59 ` Dietmar Eggemann
2020-02-13 13:54 ` Thara Gopinath
2020-02-14 10:26 ` Dietmar Eggemann
2020-02-18 14:57 ` Thara Gopinath
2020-02-19 9:14 ` Dietmar Eggemann
2020-01-28 22:36 ` [Patch v9 8/8] arm64: Enable averaging of thermal pressure for arm64 based SoCs Thara Gopinath
2020-02-03 8:59 ` Dietmar Eggemann
2020-02-10 12:07 ` [Patch v9 0/8] Introduce Thermal Pressure Dietmar Eggemann
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