From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001 From: André Fabian Silva Delgado Date: Wed, 5 Aug 2015 17:04:01 -0300 Subject: Initial import --- arch/arm/kernel/topology.c | 318 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 318 insertions(+) create mode 100644 arch/arm/kernel/topology.c (limited to 'arch/arm/kernel/topology.c') diff --git a/arch/arm/kernel/topology.c b/arch/arm/kernel/topology.c new file mode 100644 index 000000000..08b7847bf --- /dev/null +++ b/arch/arm/kernel/topology.c @@ -0,0 +1,318 @@ +/* + * arch/arm/kernel/topology.c + * + * Copyright (C) 2011 Linaro Limited. + * Written by: Vincent Guittot + * + * based on arch/sh/kernel/topology.c + * + * This file is subject to the terms and conditions of the GNU General Public + * License. See the file "COPYING" in the main directory of this archive + * for more details. + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include +#include + +/* + * cpu capacity scale management + */ + +/* + * cpu capacity table + * This per cpu data structure describes the relative capacity of each core. + * On a heteregenous system, cores don't have the same computation capacity + * and we reflect that difference in the cpu_capacity field so the scheduler + * can take this difference into account during load balance. A per cpu + * structure is preferred because each CPU updates its own cpu_capacity field + * during the load balance except for idle cores. One idle core is selected + * to run the rebalance_domains for all idle cores and the cpu_capacity can be + * updated during this sequence. + */ +static DEFINE_PER_CPU(unsigned long, cpu_scale); + +unsigned long arch_scale_cpu_capacity(struct sched_domain *sd, int cpu) +{ + return per_cpu(cpu_scale, cpu); +} + +static void set_capacity_scale(unsigned int cpu, unsigned long capacity) +{ + per_cpu(cpu_scale, cpu) = capacity; +} + +#ifdef CONFIG_OF +struct cpu_efficiency { + const char *compatible; + unsigned long efficiency; +}; + +/* + * Table of relative efficiency of each processors + * The efficiency value must fit in 20bit and the final + * cpu_scale value must be in the range + * 0 < cpu_scale < 3*SCHED_CAPACITY_SCALE/2 + * in order to return at most 1 when DIV_ROUND_CLOSEST + * is used to compute the capacity of a CPU. + * Processors that are not defined in the table, + * use the default SCHED_CAPACITY_SCALE value for cpu_scale. + */ +static const struct cpu_efficiency table_efficiency[] = { + {"arm,cortex-a15", 3891}, + {"arm,cortex-a7", 2048}, + {NULL, }, +}; + +static unsigned long *__cpu_capacity; +#define cpu_capacity(cpu) __cpu_capacity[cpu] + +static unsigned long middle_capacity = 1; + +/* + * Iterate all CPUs' descriptor in DT and compute the efficiency + * (as per table_efficiency). Also calculate a middle efficiency + * as close as possible to (max{eff_i} - min{eff_i}) / 2 + * This is later used to scale the cpu_capacity field such that an + * 'average' CPU is of middle capacity. Also see the comments near + * table_efficiency[] and update_cpu_capacity(). + */ +static void __init parse_dt_topology(void) +{ + const struct cpu_efficiency *cpu_eff; + struct device_node *cn = NULL; + unsigned long min_capacity = ULONG_MAX; + unsigned long max_capacity = 0; + unsigned long capacity = 0; + int cpu = 0; + + __cpu_capacity = kcalloc(nr_cpu_ids, sizeof(*__cpu_capacity), + GFP_NOWAIT); + + for_each_possible_cpu(cpu) { + const u32 *rate; + int len; + + /* too early to use cpu->of_node */ + cn = of_get_cpu_node(cpu, NULL); + if (!cn) { + pr_err("missing device node for CPU %d\n", cpu); + continue; + } + + for (cpu_eff = table_efficiency; cpu_eff->compatible; cpu_eff++) + if (of_device_is_compatible(cn, cpu_eff->compatible)) + break; + + if (cpu_eff->compatible == NULL) + continue; + + rate = of_get_property(cn, "clock-frequency", &len); + if (!rate || len != 4) { + pr_err("%s missing clock-frequency property\n", + cn->full_name); + continue; + } + + capacity = ((be32_to_cpup(rate)) >> 20) * cpu_eff->efficiency; + + /* Save min capacity of the system */ + if (capacity < min_capacity) + min_capacity = capacity; + + /* Save max capacity of the system */ + if (capacity > max_capacity) + max_capacity = capacity; + + cpu_capacity(cpu) = capacity; + } + + /* If min and max capacities are equals, we bypass the update of the + * cpu_scale because all CPUs have the same capacity. Otherwise, we + * compute a middle_capacity factor that will ensure that the capacity + * of an 'average' CPU of the system will be as close as possible to + * SCHED_CAPACITY_SCALE, which is the default value, but with the + * constraint explained near table_efficiency[]. + */ + if (4*max_capacity < (3*(max_capacity + min_capacity))) + middle_capacity = (min_capacity + max_capacity) + >> (SCHED_CAPACITY_SHIFT+1); + else + middle_capacity = ((max_capacity / 3) + >> (SCHED_CAPACITY_SHIFT-1)) + 1; + +} + +/* + * Look for a customed capacity of a CPU in the cpu_capacity table during the + * boot. The update of all CPUs is in O(n^2) for heteregeneous system but the + * function returns directly for SMP system. + */ +static void update_cpu_capacity(unsigned int cpu) +{ + if (!cpu_capacity(cpu)) + return; + + set_capacity_scale(cpu, cpu_capacity(cpu) / middle_capacity); + + pr_info("CPU%u: update cpu_capacity %lu\n", + cpu, arch_scale_cpu_capacity(NULL, cpu)); +} + +#else +static inline void parse_dt_topology(void) {} +static inline void update_cpu_capacity(unsigned int cpuid) {} +#endif + + /* + * cpu topology table + */ +struct cputopo_arm cpu_topology[NR_CPUS]; +EXPORT_SYMBOL_GPL(cpu_topology); + +const struct cpumask *cpu_coregroup_mask(int cpu) +{ + return &cpu_topology[cpu].core_sibling; +} + +/* + * The current assumption is that we can power gate each core independently. + * This will be superseded by DT binding once available. + */ +const struct cpumask *cpu_corepower_mask(int cpu) +{ + return &cpu_topology[cpu].thread_sibling; +} + +static void update_siblings_masks(unsigned int cpuid) +{ + struct cputopo_arm *cpu_topo, *cpuid_topo = &cpu_topology[cpuid]; + int cpu; + + /* update core and thread sibling masks */ + for_each_possible_cpu(cpu) { + cpu_topo = &cpu_topology[cpu]; + + if (cpuid_topo->socket_id != cpu_topo->socket_id) + continue; + + cpumask_set_cpu(cpuid, &cpu_topo->core_sibling); + if (cpu != cpuid) + cpumask_set_cpu(cpu, &cpuid_topo->core_sibling); + + if (cpuid_topo->core_id != cpu_topo->core_id) + continue; + + cpumask_set_cpu(cpuid, &cpu_topo->thread_sibling); + if (cpu != cpuid) + cpumask_set_cpu(cpu, &cpuid_topo->thread_sibling); + } + smp_wmb(); +} + +/* + * store_cpu_topology is called at boot when only one cpu is running + * and with the mutex cpu_hotplug.lock locked, when several cpus have booted, + * which prevents simultaneous write access to cpu_topology array + */ +void store_cpu_topology(unsigned int cpuid) +{ + struct cputopo_arm *cpuid_topo = &cpu_topology[cpuid]; + unsigned int mpidr; + + /* If the cpu topology has been already set, just return */ + if (cpuid_topo->core_id != -1) + return; + + mpidr = read_cpuid_mpidr(); + + /* create cpu topology mapping */ + if ((mpidr & MPIDR_SMP_BITMASK) == MPIDR_SMP_VALUE) { + /* + * This is a multiprocessor system + * multiprocessor format & multiprocessor mode field are set + */ + + if (mpidr & MPIDR_MT_BITMASK) { + /* core performance interdependency */ + cpuid_topo->thread_id = MPIDR_AFFINITY_LEVEL(mpidr, 0); + cpuid_topo->core_id = MPIDR_AFFINITY_LEVEL(mpidr, 1); + cpuid_topo->socket_id = MPIDR_AFFINITY_LEVEL(mpidr, 2); + } else { + /* largely independent cores */ + cpuid_topo->thread_id = -1; + cpuid_topo->core_id = MPIDR_AFFINITY_LEVEL(mpidr, 0); + cpuid_topo->socket_id = MPIDR_AFFINITY_LEVEL(mpidr, 1); + } + } else { + /* + * This is an uniprocessor system + * we are in multiprocessor format but uniprocessor system + * or in the old uniprocessor format + */ + cpuid_topo->thread_id = -1; + cpuid_topo->core_id = 0; + cpuid_topo->socket_id = -1; + } + + update_siblings_masks(cpuid); + + update_cpu_capacity(cpuid); + + pr_info("CPU%u: thread %d, cpu %d, socket %d, mpidr %x\n", + cpuid, cpu_topology[cpuid].thread_id, + cpu_topology[cpuid].core_id, + cpu_topology[cpuid].socket_id, mpidr); +} + +static inline int cpu_corepower_flags(void) +{ + return SD_SHARE_PKG_RESOURCES | SD_SHARE_POWERDOMAIN; +} + +static struct sched_domain_topology_level arm_topology[] = { +#ifdef CONFIG_SCHED_MC + { cpu_corepower_mask, cpu_corepower_flags, SD_INIT_NAME(GMC) }, + { cpu_coregroup_mask, cpu_core_flags, SD_INIT_NAME(MC) }, +#endif + { cpu_cpu_mask, SD_INIT_NAME(DIE) }, + { NULL, }, +}; + +/* + * init_cpu_topology is called at boot when only one cpu is running + * which prevent simultaneous write access to cpu_topology array + */ +void __init init_cpu_topology(void) +{ + unsigned int cpu; + + /* init core mask and capacity */ + for_each_possible_cpu(cpu) { + struct cputopo_arm *cpu_topo = &(cpu_topology[cpu]); + + cpu_topo->thread_id = -1; + cpu_topo->core_id = -1; + cpu_topo->socket_id = -1; + cpumask_clear(&cpu_topo->core_sibling); + cpumask_clear(&cpu_topo->thread_sibling); + + set_capacity_scale(cpu, SCHED_CAPACITY_SCALE); + } + smp_wmb(); + + parse_dt_topology(); + + /* Set scheduler topology descriptor */ + set_sched_topology(arm_topology); +} -- cgit v1.2.3-54-g00ecf