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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. topology_get_thermal_pressure can be hooked into the scheduler specified arch_scale_thermal_pressure 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 up to 1 tick period. Signed-off-by: Thara Gopinath <thara.gopinath@linaro.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lkml.kernel.org/r/20200222005213.3873-4-thara.gopinath@linaro.org
74 lines
1.9 KiB
C
74 lines
1.9 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* include/linux/arch_topology.h - arch specific cpu topology information
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*/
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#ifndef _LINUX_ARCH_TOPOLOGY_H_
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#define _LINUX_ARCH_TOPOLOGY_H_
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#include <linux/types.h>
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#include <linux/percpu.h>
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void topology_normalize_cpu_scale(void);
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int topology_update_cpu_topology(void);
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struct device_node;
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bool topology_parse_cpu_capacity(struct device_node *cpu_node, int cpu);
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DECLARE_PER_CPU(unsigned long, cpu_scale);
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struct sched_domain;
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static inline
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unsigned long topology_get_cpu_scale(int cpu)
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{
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return per_cpu(cpu_scale, cpu);
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}
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void topology_set_cpu_scale(unsigned int cpu, unsigned long capacity);
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DECLARE_PER_CPU(unsigned long, freq_scale);
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static inline
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unsigned long topology_get_freq_scale(int cpu)
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{
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return per_cpu(freq_scale, cpu);
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}
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DECLARE_PER_CPU(unsigned long, thermal_pressure);
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static inline unsigned long topology_get_thermal_pressure(int cpu)
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{
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return per_cpu(thermal_pressure, cpu);
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}
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void arch_set_thermal_pressure(struct cpumask *cpus,
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unsigned long th_pressure);
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struct cpu_topology {
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int thread_id;
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int core_id;
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int package_id;
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int llc_id;
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cpumask_t thread_sibling;
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cpumask_t core_sibling;
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cpumask_t llc_sibling;
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};
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#ifdef CONFIG_GENERIC_ARCH_TOPOLOGY
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extern struct cpu_topology cpu_topology[NR_CPUS];
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#define topology_physical_package_id(cpu) (cpu_topology[cpu].package_id)
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#define topology_core_id(cpu) (cpu_topology[cpu].core_id)
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#define topology_core_cpumask(cpu) (&cpu_topology[cpu].core_sibling)
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#define topology_sibling_cpumask(cpu) (&cpu_topology[cpu].thread_sibling)
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#define topology_llc_cpumask(cpu) (&cpu_topology[cpu].llc_sibling)
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void init_cpu_topology(void);
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void store_cpu_topology(unsigned int cpuid);
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const struct cpumask *cpu_coregroup_mask(int cpu);
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void update_siblings_masks(unsigned int cpu);
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void remove_cpu_topology(unsigned int cpuid);
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void reset_cpu_topology(void);
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int parse_acpi_topology(void);
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#endif
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#endif /* _LINUX_ARCH_TOPOLOGY_H_ */
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