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@@ -17,11 +17,190 @@
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#include <linux/percpu.h>
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#include <linux/node.h>
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#include <linux/nodemask.h>
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+#include <linux/of.h>
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#include <linux/sched.h>
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+#include <linux/slab.h>
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#include <asm/cputype.h>
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#include <asm/topology.h>
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+/*
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+ * cpu power scale management
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+ */
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+
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+/*
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+ * cpu power table
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+ * This per cpu data structure describes the relative capacity of each core.
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+ * On a heteregenous system, cores don't have the same computation capacity
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+ * and we reflect that difference in the cpu_power field so the scheduler can
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+ * take this difference into account during load balance. A per cpu structure
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+ * is preferred because each CPU updates its own cpu_power field during the
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+ * load balance except for idle cores. One idle core is selected to run the
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+ * rebalance_domains for all idle cores and the cpu_power can be updated
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+ * during this sequence.
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+ */
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+static DEFINE_PER_CPU(unsigned long, cpu_scale);
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+
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+unsigned long arch_scale_freq_power(struct sched_domain *sd, int cpu)
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+{
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+ return per_cpu(cpu_scale, cpu);
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+}
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+
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+static void set_power_scale(unsigned int cpu, unsigned long power)
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+{
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+ per_cpu(cpu_scale, cpu) = power;
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+}
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+
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+#ifdef CONFIG_OF
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+struct cpu_efficiency {
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+ const char *compatible;
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+ unsigned long efficiency;
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+};
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+
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+/*
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+ * Table of relative efficiency of each processors
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+ * The efficiency value must fit in 20bit and the final
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+ * cpu_scale value must be in the range
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+ * 0 < cpu_scale < 3*SCHED_POWER_SCALE/2
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+ * in order to return at most 1 when DIV_ROUND_CLOSEST
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+ * is used to compute the capacity of a CPU.
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+ * Processors that are not defined in the table,
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+ * use the default SCHED_POWER_SCALE value for cpu_scale.
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+ */
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+struct cpu_efficiency table_efficiency[] = {
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+ {"arm,cortex-a15", 3891},
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+ {"arm,cortex-a7", 2048},
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+ {NULL, },
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+};
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+
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+struct cpu_capacity {
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+ unsigned long hwid;
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+ unsigned long capacity;
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+};
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+
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+struct cpu_capacity *cpu_capacity;
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+
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+unsigned long middle_capacity = 1;
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+
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+/*
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+ * Iterate all CPUs' descriptor in DT and compute the efficiency
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+ * (as per table_efficiency). Also calculate a middle efficiency
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+ * as close as possible to (max{eff_i} - min{eff_i}) / 2
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+ * This is later used to scale the cpu_power field such that an
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+ * 'average' CPU is of middle power. Also see the comments near
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+ * table_efficiency[] and update_cpu_power().
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+ */
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+static void __init parse_dt_topology(void)
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+{
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+ struct cpu_efficiency *cpu_eff;
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+ struct device_node *cn = NULL;
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+ unsigned long min_capacity = (unsigned long)(-1);
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+ unsigned long max_capacity = 0;
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+ unsigned long capacity = 0;
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+ int alloc_size, cpu = 0;
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+
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+ alloc_size = nr_cpu_ids * sizeof(struct cpu_capacity);
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+ cpu_capacity = (struct cpu_capacity *)kzalloc(alloc_size, GFP_NOWAIT);
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+
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+ while ((cn = of_find_node_by_type(cn, "cpu"))) {
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+ const u32 *rate, *reg;
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+ int len;
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+
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+ if (cpu >= num_possible_cpus())
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+ break;
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+
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+ for (cpu_eff = table_efficiency; cpu_eff->compatible; cpu_eff++)
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+ if (of_device_is_compatible(cn, cpu_eff->compatible))
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+ break;
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+
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+ if (cpu_eff->compatible == NULL)
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+ continue;
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+
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+ rate = of_get_property(cn, "clock-frequency", &len);
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+ if (!rate || len != 4) {
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+ pr_err("%s missing clock-frequency property\n",
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+ cn->full_name);
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+ continue;
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+ }
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+
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+ reg = of_get_property(cn, "reg", &len);
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+ if (!reg || len != 4) {
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+ pr_err("%s missing reg property\n", cn->full_name);
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+ continue;
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+ }
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+
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+ capacity = ((be32_to_cpup(rate)) >> 20) * cpu_eff->efficiency;
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+
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+ /* Save min capacity of the system */
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+ if (capacity < min_capacity)
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+ min_capacity = capacity;
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+
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+ /* Save max capacity of the system */
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+ if (capacity > max_capacity)
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+ max_capacity = capacity;
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+
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+ cpu_capacity[cpu].capacity = capacity;
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+ cpu_capacity[cpu++].hwid = be32_to_cpup(reg);
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+ }
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+
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+ if (cpu < num_possible_cpus())
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+ cpu_capacity[cpu].hwid = (unsigned long)(-1);
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+
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+ /* If min and max capacities are equals, we bypass the update of the
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+ * cpu_scale because all CPUs have the same capacity. Otherwise, we
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+ * compute a middle_capacity factor that will ensure that the capacity
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+ * of an 'average' CPU of the system will be as close as possible to
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+ * SCHED_POWER_SCALE, which is the default value, but with the
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+ * constraint explained near table_efficiency[].
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+ */
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+ if (min_capacity == max_capacity)
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+ cpu_capacity[0].hwid = (unsigned long)(-1);
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+ else if (4*max_capacity < (3*(max_capacity + min_capacity)))
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+ middle_capacity = (min_capacity + max_capacity)
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+ >> (SCHED_POWER_SHIFT+1);
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+ else
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+ middle_capacity = ((max_capacity / 3)
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+ >> (SCHED_POWER_SHIFT-1)) + 1;
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+
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+}
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+
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+/*
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+ * Look for a customed capacity of a CPU in the cpu_capacity table during the
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+ * boot. The update of all CPUs is in O(n^2) for heteregeneous system but the
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+ * function returns directly for SMP system.
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+ */
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+void update_cpu_power(unsigned int cpu, unsigned long hwid)
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+{
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+ unsigned int idx = 0;
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+
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+ /* look for the cpu's hwid in the cpu capacity table */
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+ for (idx = 0; idx < num_possible_cpus(); idx++) {
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+ if (cpu_capacity[idx].hwid == hwid)
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+ break;
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+
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+ if (cpu_capacity[idx].hwid == -1)
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+ return;
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+ }
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+
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+ if (idx == num_possible_cpus())
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+ return;
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+
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+ set_power_scale(cpu, cpu_capacity[idx].capacity / middle_capacity);
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+
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+ printk(KERN_INFO "CPU%u: update cpu_power %lu\n",
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+ cpu, arch_scale_freq_power(NULL, cpu));
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+}
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+
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+#else
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+static inline void parse_dt_topology(void) {}
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+static inline void update_cpu_power(unsigned int cpuid, unsigned int mpidr) {}
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+#endif
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+
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+
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+/*
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+ * cpu topology management
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+ */
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+
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#define MPIDR_SMP_BITMASK (0x3 << 30)
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#define MPIDR_SMP_VALUE (0x2 << 30)
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@@ -31,6 +210,7 @@
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* These masks reflect the current use of the affinity levels.
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* The affinity level can be up to 16 bits according to ARM ARM
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*/
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+#define MPIDR_HWID_BITMASK 0xFFFFFF
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#define MPIDR_LEVEL0_MASK 0x3
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#define MPIDR_LEVEL0_SHIFT 0
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@@ -41,6 +221,9 @@
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#define MPIDR_LEVEL2_MASK 0xFF
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#define MPIDR_LEVEL2_SHIFT 16
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+/*
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+ * cpu topology table
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+ */
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struct cputopo_arm cpu_topology[NR_CPUS];
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const struct cpumask *cpu_coregroup_mask(int cpu)
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@@ -48,6 +231,32 @@ const struct cpumask *cpu_coregroup_mask(int cpu)
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return &cpu_topology[cpu].core_sibling;
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}
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+void update_siblings_masks(unsigned int cpuid)
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+{
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+ struct cputopo_arm *cpu_topo, *cpuid_topo = &cpu_topology[cpuid];
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+ int cpu;
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+
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+ /* update core and thread sibling masks */
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+ for_each_possible_cpu(cpu) {
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+ cpu_topo = &cpu_topology[cpu];
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+
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+ if (cpuid_topo->socket_id != cpu_topo->socket_id)
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+ continue;
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+
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+ cpumask_set_cpu(cpuid, &cpu_topo->core_sibling);
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+ if (cpu != cpuid)
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+ cpumask_set_cpu(cpu, &cpuid_topo->core_sibling);
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+
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+ if (cpuid_topo->core_id != cpu_topo->core_id)
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+ continue;
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+
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+ cpumask_set_cpu(cpuid, &cpu_topo->thread_sibling);
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+ if (cpu != cpuid)
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+ cpumask_set_cpu(cpu, &cpuid_topo->thread_sibling);
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+ }
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+ smp_wmb();
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+}
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+
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/*
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* store_cpu_topology is called at boot when only one cpu is running
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* and with the mutex cpu_hotplug.lock locked, when several cpus have booted,
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@@ -57,7 +266,6 @@ void store_cpu_topology(unsigned int cpuid)
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{
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struct cputopo_arm *cpuid_topo = &cpu_topology[cpuid];
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unsigned int mpidr;
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- unsigned int cpu;
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/* If the cpu topology has been already set, just return */
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if (cpuid_topo->core_id != -1)
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@@ -99,26 +307,9 @@ void store_cpu_topology(unsigned int cpuid)
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cpuid_topo->socket_id = -1;
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}
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- /* update core and thread sibling masks */
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- for_each_possible_cpu(cpu) {
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- struct cputopo_arm *cpu_topo = &cpu_topology[cpu];
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-
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- if (cpuid_topo->socket_id == cpu_topo->socket_id) {
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- cpumask_set_cpu(cpuid, &cpu_topo->core_sibling);
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- if (cpu != cpuid)
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- cpumask_set_cpu(cpu,
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- &cpuid_topo->core_sibling);
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-
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- if (cpuid_topo->core_id == cpu_topo->core_id) {
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- cpumask_set_cpu(cpuid,
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- &cpu_topo->thread_sibling);
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- if (cpu != cpuid)
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- cpumask_set_cpu(cpu,
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- &cpuid_topo->thread_sibling);
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- }
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- }
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- }
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- smp_wmb();
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+ update_siblings_masks(cpuid);
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+
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+ update_cpu_power(cpuid, mpidr & MPIDR_HWID_BITMASK);
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printk(KERN_INFO "CPU%u: thread %d, cpu %d, socket %d, mpidr %x\n",
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cpuid, cpu_topology[cpuid].thread_id,
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@@ -134,7 +325,7 @@ void init_cpu_topology(void)
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{
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unsigned int cpu;
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- /* init core mask */
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+ /* init core mask and power*/
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for_each_possible_cpu(cpu) {
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struct cputopo_arm *cpu_topo = &(cpu_topology[cpu]);
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@@ -143,6 +334,10 @@ void init_cpu_topology(void)
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cpu_topo->socket_id = -1;
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cpumask_clear(&cpu_topo->core_sibling);
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cpumask_clear(&cpu_topo->thread_sibling);
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+
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+ set_power_scale(cpu, SCHED_POWER_SCALE);
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}
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smp_wmb();
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+
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+ parse_dt_topology();
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}
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