| Message ID | 1576123908-12105-4-git-send-email-thara.gopinath@linaro.org |
|---|---|
| State | New |
| Headers | show |
| Series | Introduce Thermal Pressure | expand |
On Wed, Dec 11, 2019 at 11:11:44PM -0500, Thara Gopinath wrote: > diff --git a/arch/arm/include/asm/topology.h b/arch/arm/include/asm/topology.h > index 8a0fae9..90b18c3 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 defalut thermal pressure retrieve API */ > +#define arch_scale_thermal_capacity topology_get_thermal_pressure Witsness the previously observed confusion. > #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..ccb277b 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 defalut thermal pressure retrieve API */ > +#define arch_scale_thermal_capacity 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 1eb81f11..3a91379 100644 > --- a/drivers/base/arch_topology.c > +++ b/drivers/base/arch_topology.c > @@ -42,6 +42,19 @@ 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 capped_capacity) > +{ > + int cpu; > + unsigned long delta = arch_scale_cpu_capacity(cpumask_first(cpus)) - > + capped_capacity; > + > + for_each_cpu(cpu, cpus) > + WRITE_ONCE(per_cpu(thermal_pressure, cpu), delta); > +} Not a capacity. > static ssize_t cpu_capacity_show(struct device *dev, > struct device_attribute *attr, > char *buf) > diff --git a/include/linux/arch_topology.h b/include/linux/arch_topology.h > index 3015ecb..7a04364 100644 > --- a/include/linux/arch_topology.h > +++ b/include/linux/arch_topology.h > @@ -33,6 +33,17 @@ unsigned long topology_get_freq_scale(int cpu) > return per_cpu(freq_scale, cpu); > } > > +DECLARE_PER_CPU(unsigned long, thermal_pressure); > + > +static inline > +unsigned long topology_get_thermal_pressure(int cpu) > +{ > + return per_cpu(thermal_pressure, cpu); > +}
On 12/12/2019 05:11, Thara Gopinath wrote: Shouldn't the subject contain something like 'arm,arm64,drivers:' ? > 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. > capacity and capped capacity due to a thermal event. > > topology_get_thermal_pressure can be hooked into the scheduler specified > arch_scale_thermal_capacity to retrieve instantaneius thermal pressure of s/instantaneius/instantaneous > a cpu. > > arch_set_thermal_presure can be used to update the thermal pressure by s/presure/pressure > providing a capped maximum capacity. > > 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_average can be called from a system critical s/topology_get_thermal_pressure_average/topology_get_thermal_pressure ? > 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> > --- > > v3->v4: > - Dropped per cpu max_capacity_info struct and instead added a per > delta_capacity variable to store the delta between maximum > capacity and capped capacity. The delta is now calculated when > thermal pressure is updated and not every tick. > - Dropped populate_max_capacity_info api as only per cpu delta > capacity is stored. > - Renamed update_periodic_maxcap to > trigger_thermal_pressure_average and update_maxcap_capacity to > update_thermal_pressure. > v4->v5: > - As per Peter's review comments folded thermal.c into fair.c. > - As per Ionela's review comments revamped update_thermal_pressure > to take maximum available capacity as input instead of maximum > capped frequency ration. > v5->v6: > - As per review comments moved all the infrastructure to track > and retrieve instantaneous thermal pressure out of scheduler > to topology files. > > arch/arm/include/asm/topology.h | 3 +++ > arch/arm64/include/asm/topology.h | 3 +++ > drivers/base/arch_topology.c | 13 +++++++++++++ > include/linux/arch_topology.h | 11 +++++++++++ > 4 files changed, 30 insertions(+) > > diff --git a/arch/arm/include/asm/topology.h b/arch/arm/include/asm/topology.h > index 8a0fae9..90b18c3 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 defalut thermal pressure retrieve API */ > +#define arch_scale_thermal_capacity 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..ccb277b 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 defalut thermal pressure retrieve API */ > +#define arch_scale_thermal_capacity 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 1eb81f11..3a91379 100644 > --- a/drivers/base/arch_topology.c > +++ b/drivers/base/arch_topology.c > @@ -42,6 +42,19 @@ 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 capped_capacity) > +{ > + int cpu; > + unsigned long delta = arch_scale_cpu_capacity(cpumask_first(cpus)) - > + capped_capacity; unsigned long delta; int cpu; delta = arch_scale_cpu_capacity(cpumask_first(cpus)) - capped_capacity; Easier to read plus order local variable declarations from longest to shortest line. https://lore.kernel.org/r/20181107171149.165693799@linutronix.de > + > + for_each_cpu(cpu, cpus) > + WRITE_ONCE(per_cpu(thermal_pressure, cpu), delta); > +} > + > static ssize_t cpu_capacity_show(struct device *dev, > struct device_attribute *attr, > char *buf) > diff --git a/include/linux/arch_topology.h b/include/linux/arch_topology.h > index 3015ecb..7a04364 100644 > --- a/include/linux/arch_topology.h > +++ b/include/linux/arch_topology.h > @@ -33,6 +33,17 @@ unsigned long topology_get_freq_scale(int cpu) > return per_cpu(freq_scale, cpu); > } > > +DECLARE_PER_CPU(unsigned long, thermal_pressure); > + > +static inline > +unsigned long topology_get_thermal_pressure(int cpu) Save one line: static inline unsigned long topology_get_thermal_pressure(int cpu) > +{ > + return per_cpu(thermal_pressure, cpu); > +} > + > +void arch_set_thermal_pressure(struct cpumask *cpus, > + unsigned long capped_capacity); > + > struct cpu_topology { > int thread_id; > int core_id; >
Hi Thara, On Wednesday 11 Dec 2019 at 23:11:44 (-0500), Thara Gopinath 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. > capacity and capped capacity due to a thermal event. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ This line seems to be a duplicate (initially I thought I was seeing double :) ). > topology_get_thermal_pressure can be hooked into the scheduler specified > arch_scale_thermal_capacity to retrieve instantaneius thermal pressure of > a cpu. > > arch_set_thermal_presure can be used to update the thermal pressure by > providing a capped maximum capacity. > > 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_average 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> [...] > diff --git a/arch/arm/include/asm/topology.h b/arch/arm/include/asm/topology.h > index 8a0fae9..90b18c3 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 defalut thermal pressure retrieve API */ s/defalut/default > +#define arch_scale_thermal_capacity topology_get_thermal_pressure > + I also think this is deserving of a better name. I would drop the 'scale' part as well as it is not used as a scale factor, as freq_scale or cpu_scale, but it's used as a reduction in capacity (thermal capacity pressure) due to a thermal event. It might be too much but what do you think about: arch_thermal_capacity_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..ccb277b 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 defalut thermal pressure retrieve API */ s/defalut/default Regards, Ionela.
diff --git a/arch/arm/include/asm/topology.h b/arch/arm/include/asm/topology.h index 8a0fae9..90b18c3 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 defalut thermal pressure retrieve API */ +#define arch_scale_thermal_capacity 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..ccb277b 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 defalut thermal pressure retrieve API */ +#define arch_scale_thermal_capacity 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 1eb81f11..3a91379 100644 --- a/drivers/base/arch_topology.c +++ b/drivers/base/arch_topology.c @@ -42,6 +42,19 @@ 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 capped_capacity) +{ + int cpu; + unsigned long delta = arch_scale_cpu_capacity(cpumask_first(cpus)) - + capped_capacity; + + for_each_cpu(cpu, cpus) + WRITE_ONCE(per_cpu(thermal_pressure, cpu), delta); +} + static ssize_t cpu_capacity_show(struct device *dev, struct device_attribute *attr, char *buf) diff --git a/include/linux/arch_topology.h b/include/linux/arch_topology.h index 3015ecb..7a04364 100644 --- a/include/linux/arch_topology.h +++ b/include/linux/arch_topology.h @@ -33,6 +33,17 @@ unsigned long topology_get_freq_scale(int cpu) return per_cpu(freq_scale, cpu); } +DECLARE_PER_CPU(unsigned long, thermal_pressure); + +static inline +unsigned long topology_get_thermal_pressure(int cpu) +{ + return per_cpu(thermal_pressure, cpu); +} + +void arch_set_thermal_pressure(struct cpumask *cpus, + unsigned long capped_capacity); + struct cpu_topology { int thread_id; int core_id;
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. capacity and capped capacity due to a thermal event. topology_get_thermal_pressure can be hooked into the scheduler specified arch_scale_thermal_capacity to retrieve instantaneius thermal pressure of a cpu. arch_set_thermal_presure can be used to update the thermal pressure by providing a capped maximum capacity. 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_average 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> --- v3->v4: - Dropped per cpu max_capacity_info struct and instead added a per delta_capacity variable to store the delta between maximum capacity and capped capacity. The delta is now calculated when thermal pressure is updated and not every tick. - Dropped populate_max_capacity_info api as only per cpu delta capacity is stored. - Renamed update_periodic_maxcap to trigger_thermal_pressure_average and update_maxcap_capacity to update_thermal_pressure. v4->v5: - As per Peter's review comments folded thermal.c into fair.c. - As per Ionela's review comments revamped update_thermal_pressure to take maximum available capacity as input instead of maximum capped frequency ration. v5->v6: - As per review comments moved all the infrastructure to track and retrieve instantaneous thermal pressure out of scheduler to topology files. arch/arm/include/asm/topology.h | 3 +++ arch/arm64/include/asm/topology.h | 3 +++ drivers/base/arch_topology.c | 13 +++++++++++++ include/linux/arch_topology.h | 11 +++++++++++ 4 files changed, 30 insertions(+) -- 2.1.4