--- /dev/null
+/* cpumap.c: used for optimizing CPU assignment
+ *
+ * Copyright (C) 2009 Hong H. Pham <hong.pham@windriver.com>
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/cpumask.h>
+#include <linux/spinlock.h>
+#include <asm/cpudata.h>
+#include "cpumap.h"
+
+
+enum {
+ CPUINFO_LVL_ROOT = 0,
+ CPUINFO_LVL_NODE,
+ CPUINFO_LVL_CORE,
+ CPUINFO_LVL_PROC,
+ CPUINFO_LVL_MAX,
+};
+
+enum {
+ ROVER_NO_OP = 0,
+ /* Increment rover every time level is visited */
+ ROVER_INC_ON_VISIT = 1 << 0,
+ /* Increment parent's rover every time rover wraps around */
+ ROVER_INC_PARENT_ON_LOOP = 1 << 1,
+};
+
+struct cpuinfo_node {
+ int id;
+ int level;
+ int num_cpus; /* Number of CPUs in this hierarchy */
+ int parent_index;
+ int child_start; /* Array index of the first child node */
+ int child_end; /* Array index of the last child node */
+ int rover; /* Child node iterator */
+};
+
+struct cpuinfo_level {
+ int start_index; /* Index of first node of a level in a cpuinfo tree */
+ int end_index; /* Index of last node of a level in a cpuinfo tree */
+ int num_nodes; /* Number of nodes in a level in a cpuinfo tree */
+};
+
+struct cpuinfo_tree {
+ int total_nodes;
+
+ /* Offsets into nodes[] for each level of the tree */
+ struct cpuinfo_level level[CPUINFO_LVL_MAX];
+ struct cpuinfo_node nodes[0];
+};
+
+
+static struct cpuinfo_tree *cpuinfo_tree;
+
+static u16 cpu_distribution_map[NR_CPUS];
+static DEFINE_SPINLOCK(cpu_map_lock);
+
+
+/* Niagara optimized cpuinfo tree traversal. */
+static const int niagara_iterate_method[] = {
+ [CPUINFO_LVL_ROOT] = ROVER_NO_OP,
+
+ /* Strands (or virtual CPUs) within a core may not run concurrently
+ * on the Niagara, as instruction pipeline(s) are shared. Distribute
+ * work to strands in different cores first for better concurrency.
+ * Go to next NUMA node when all cores are used.
+ */
+ [CPUINFO_LVL_NODE] = ROVER_INC_ON_VISIT|ROVER_INC_PARENT_ON_LOOP,
+
+ /* Strands are grouped together by proc_id in cpuinfo_sparc, i.e.
+ * a proc_id represents an instruction pipeline. Distribute work to
+ * strands in different proc_id groups if the core has multiple
+ * instruction pipelines (e.g. the Niagara 2/2+ has two).
+ */
+ [CPUINFO_LVL_CORE] = ROVER_INC_ON_VISIT,
+
+ /* Pick the next strand in the proc_id group. */
+ [CPUINFO_LVL_PROC] = ROVER_INC_ON_VISIT,
+};
+
+/* Generic cpuinfo tree traversal. Distribute work round robin across NUMA
+ * nodes.
+ */
+static const int generic_iterate_method[] = {
+ [CPUINFO_LVL_ROOT] = ROVER_INC_ON_VISIT,
+ [CPUINFO_LVL_NODE] = ROVER_NO_OP,
+ [CPUINFO_LVL_CORE] = ROVER_INC_PARENT_ON_LOOP,
+ [CPUINFO_LVL_PROC] = ROVER_INC_ON_VISIT|ROVER_INC_PARENT_ON_LOOP,
+};
+
+
+static int cpuinfo_id(int cpu, int level)
+{
+ int id;
+
+ switch (level) {
+ case CPUINFO_LVL_ROOT:
+ id = 0;
+ break;
+ case CPUINFO_LVL_NODE:
+ id = cpu_to_node(cpu);
+ break;
+ case CPUINFO_LVL_CORE:
+ id = cpu_data(cpu).core_id;
+ break;
+ case CPUINFO_LVL_PROC:
+ id = cpu_data(cpu).proc_id;
+ break;
+ default:
+ id = -EINVAL;
+ }
+ return id;
+}
+
+/*
+ * Enumerate the CPU information in __cpu_data to determine the start index,
+ * end index, and number of nodes for each level in the cpuinfo tree. The
+ * total number of cpuinfo nodes required to build the tree is returned.
+ */
+static int enumerate_cpuinfo_nodes(struct cpuinfo_level *tree_level)
+{
+ int prev_id[CPUINFO_LVL_MAX];
+ int i, n, num_nodes;
+
+ for (i = CPUINFO_LVL_ROOT; i < CPUINFO_LVL_MAX; i++) {
+ struct cpuinfo_level *lv = &tree_level[i];
+
+ prev_id[i] = -1;
+ lv->start_index = lv->end_index = lv->num_nodes = 0;
+ }
+
+ num_nodes = 1; /* Include the root node */
+
+ for (i = 0; i < num_possible_cpus(); i++) {
+ if (!cpu_online(i))
+ continue;
+
+ n = cpuinfo_id(i, CPUINFO_LVL_NODE);
+ if (n > prev_id[CPUINFO_LVL_NODE]) {
+ tree_level[CPUINFO_LVL_NODE].num_nodes++;
+ prev_id[CPUINFO_LVL_NODE] = n;
+ num_nodes++;
+ }
+ n = cpuinfo_id(i, CPUINFO_LVL_CORE);
+ if (n > prev_id[CPUINFO_LVL_CORE]) {
+ tree_level[CPUINFO_LVL_CORE].num_nodes++;
+ prev_id[CPUINFO_LVL_CORE] = n;
+ num_nodes++;
+ }
+ n = cpuinfo_id(i, CPUINFO_LVL_PROC);
+ if (n > prev_id[CPUINFO_LVL_PROC]) {
+ tree_level[CPUINFO_LVL_PROC].num_nodes++;
+ prev_id[CPUINFO_LVL_PROC] = n;
+ num_nodes++;
+ }
+ }
+
+ tree_level[CPUINFO_LVL_ROOT].num_nodes = 1;
+
+ n = tree_level[CPUINFO_LVL_NODE].num_nodes;
+ tree_level[CPUINFO_LVL_NODE].start_index = 1;
+ tree_level[CPUINFO_LVL_NODE].end_index = n;
+
+ n++;
+ tree_level[CPUINFO_LVL_CORE].start_index = n;
+ n += tree_level[CPUINFO_LVL_CORE].num_nodes;
+ tree_level[CPUINFO_LVL_CORE].end_index = n - 1;
+
+ tree_level[CPUINFO_LVL_PROC].start_index = n;
+ n += tree_level[CPUINFO_LVL_PROC].num_nodes;
+ tree_level[CPUINFO_LVL_PROC].end_index = n - 1;
+
+ return num_nodes;
+}
+
+/* Build a tree representation of the CPU hierarchy using the per CPU
+ * information in __cpu_data. Entries in __cpu_data[0..NR_CPUS] are
+ * assumed to be sorted in ascending order based on node, core_id, and
+ * proc_id (in order of significance).
+ */
+static struct cpuinfo_tree *build_cpuinfo_tree(void)
+{
+ struct cpuinfo_tree *new_tree;
+ struct cpuinfo_node *node;
+ struct cpuinfo_level tmp_level[CPUINFO_LVL_MAX];
+ int num_cpus[CPUINFO_LVL_MAX];
+ int level_rover[CPUINFO_LVL_MAX];
+ int prev_id[CPUINFO_LVL_MAX];
+ int n, id, cpu, prev_cpu, last_cpu, level;
+
+ n = enumerate_cpuinfo_nodes(tmp_level);
+
+ new_tree = kzalloc(sizeof(struct cpuinfo_tree) +
+ (sizeof(struct cpuinfo_node) * n), GFP_ATOMIC);
+ if (!new_tree)
+ return NULL;
+
+ new_tree->total_nodes = n;
+ memcpy(&new_tree->level, tmp_level, sizeof(tmp_level));
+
+ prev_cpu = cpu = first_cpu(cpu_online_map);
+
+ /* Initialize all levels in the tree with the first CPU */
+ for (level = CPUINFO_LVL_PROC; level >= CPUINFO_LVL_ROOT; level--) {
+ n = new_tree->level[level].start_index;
+
+ level_rover[level] = n;
+ node = &new_tree->nodes[n];
+
+ id = cpuinfo_id(cpu, level);
+ if (unlikely(id < 0)) {
+ kfree(new_tree);
+ return NULL;
+ }
+ node->id = id;
+ node->level = level;
+ node->num_cpus = 1;
+
+ node->parent_index = (level > CPUINFO_LVL_ROOT)
+ ? new_tree->level[level - 1].start_index : -1;
+
+ node->child_start = node->child_end = node->rover =
+ (level == CPUINFO_LVL_PROC)
+ ? cpu : new_tree->level[level + 1].start_index;
+
+ prev_id[level] = node->id;
+ num_cpus[level] = 1;
+ }
+
+ for (last_cpu = (num_possible_cpus() - 1); last_cpu >= 0; last_cpu--) {
+ if (cpu_online(last_cpu))
+ break;
+ }
+
+ while (++cpu <= last_cpu) {
+ if (!cpu_online(cpu))
+ continue;
+
+ for (level = CPUINFO_LVL_PROC; level >= CPUINFO_LVL_ROOT;
+ level--) {
+ id = cpuinfo_id(cpu, level);
+ if (unlikely(id < 0)) {
+ kfree(new_tree);
+ return NULL;
+ }
+
+ if ((id != prev_id[level]) || (cpu == last_cpu)) {
+ prev_id[level] = id;
+ node = &new_tree->nodes[level_rover[level]];
+ node->num_cpus = num_cpus[level];
+ num_cpus[level] = 1;
+
+ if (cpu == last_cpu)
+ node->num_cpus++;
+
+ /* Connect tree node to parent */
+ if (level == CPUINFO_LVL_ROOT)
+ node->parent_index = -1;
+ else
+ node->parent_index =
+ level_rover[level - 1];
+
+ if (level == CPUINFO_LVL_PROC) {
+ node->child_end =
+ (cpu == last_cpu) ? cpu : prev_cpu;
+ } else {
+ node->child_end =
+ level_rover[level + 1] - 1;
+ }
+
+ /* Initialize the next node in the same level */
+ n = ++level_rover[level];
+ if (n <= new_tree->level[level].end_index) {
+ node = &new_tree->nodes[n];
+ node->id = id;
+ node->level = level;
+
+ /* Connect node to child */
+ node->child_start = node->child_end =
+ node->rover =
+ (level == CPUINFO_LVL_PROC)
+ ? cpu : level_rover[level + 1];
+ }
+ } else
+ num_cpus[level]++;
+ }
+ prev_cpu = cpu;
+ }
+
+ return new_tree;
+}
+
+static void increment_rover(struct cpuinfo_tree *t, int node_index,
+ int root_index, const int *rover_inc_table)
+{
+ struct cpuinfo_node *node = &t->nodes[node_index];
+ int top_level, level;
+
+ top_level = t->nodes[root_index].level;
+ for (level = node->level; level >= top_level; level--) {
+ node->rover++;
+ if (node->rover <= node->child_end)
+ return;
+
+ node->rover = node->child_start;
+ /* If parent's rover does not need to be adjusted, stop here. */
+ if ((level == top_level) ||
+ !(rover_inc_table[level] & ROVER_INC_PARENT_ON_LOOP))
+ return;
+
+ node = &t->nodes[node->parent_index];
+ }
+}
+
+static int iterate_cpu(struct cpuinfo_tree *t, unsigned int root_index)
+{
+ const int *rover_inc_table;
+ int level, new_index, index = root_index;
+
+ switch (sun4v_chip_type) {
+ case SUN4V_CHIP_NIAGARA1:
+ case SUN4V_CHIP_NIAGARA2:
+ rover_inc_table = niagara_iterate_method;
+ break;
+ default:
+ rover_inc_table = generic_iterate_method;
+ }
+
+ for (level = t->nodes[root_index].level; level < CPUINFO_LVL_MAX;
+ level++) {
+ new_index = t->nodes[index].rover;
+ if (rover_inc_table[level] & ROVER_INC_ON_VISIT)
+ increment_rover(t, index, root_index, rover_inc_table);
+
+ index = new_index;
+ }
+ return index;
+}
+
+static void _cpu_map_rebuild(void)
+{
+ int i;
+
+ if (cpuinfo_tree) {
+ kfree(cpuinfo_tree);
+ cpuinfo_tree = NULL;
+ }
+
+ cpuinfo_tree = build_cpuinfo_tree();
+ if (!cpuinfo_tree)
+ return;
+
+ /* Build CPU distribution map that spans all online CPUs. No need
+ * to check if the CPU is online, as that is done when the cpuinfo
+ * tree is being built.
+ */
+ for (i = 0; i < cpuinfo_tree->nodes[0].num_cpus; i++)
+ cpu_distribution_map[i] = iterate_cpu(cpuinfo_tree, 0);
+}
+
+/* Fallback if the cpuinfo tree could not be built. CPU mapping is linear
+ * round robin.
+ */
+static int simple_map_to_cpu(unsigned int index)
+{
+ int i, end, cpu_rover;
+
+ cpu_rover = 0;
+ end = index % num_online_cpus();
+ for (i = 0; i < num_possible_cpus(); i++) {
+ if (cpu_online(cpu_rover)) {
+ if (cpu_rover >= end)
+ return cpu_rover;
+
+ cpu_rover++;
+ }
+ }
+
+ /* Impossible, since num_online_cpus() <= num_possible_cpus() */
+ return first_cpu(cpu_online_map);
+}
+
+static int _map_to_cpu(unsigned int index)
+{
+ struct cpuinfo_node *root_node;
+
+ if (unlikely(!cpuinfo_tree)) {
+ _cpu_map_rebuild();
+ if (!cpuinfo_tree)
+ return simple_map_to_cpu(index);
+ }
+
+ root_node = &cpuinfo_tree->nodes[0];
+#ifdef CONFIG_HOTPLUG_CPU
+ if (unlikely(root_node->num_cpus != num_online_cpus())) {
+ _cpu_map_rebuild();
+ if (!cpuinfo_tree)
+ return simple_map_to_cpu(index);
+ }
+#endif
+ return cpu_distribution_map[index % root_node->num_cpus];
+}
+
+int map_to_cpu(unsigned int index)
+{
+ int mapped_cpu;
+ unsigned long flag;
+
+ spin_lock_irqsave(&cpu_map_lock, flag);
+ mapped_cpu = _map_to_cpu(index);
+
+#ifdef CONFIG_HOTPLUG_CPU
+ while (unlikely(!cpu_online(mapped_cpu)))
+ mapped_cpu = _map_to_cpu(index);
+#endif
+ spin_unlock_irqrestore(&cpu_map_lock, flag);
+ return mapped_cpu;
+}
+EXPORT_SYMBOL(map_to_cpu);
+
+void cpu_map_rebuild(void)
+{
+ unsigned long flag;
+
+ spin_lock_irqsave(&cpu_map_lock, flag);
+ _cpu_map_rebuild();
+ spin_unlock_irqrestore(&cpu_map_lock, flag);
+}
projects / platform / kernel / linux-amlogic.git / commitdiff