linux/arch/sparc/kernel/cpumap.c
Paul Gortmaker 066bcaca51 sparc: move symbol exporters to use export.h not module.h
Many of the core sparc kernel files are not modules, but just
including module.h for exporting symbols.  Now these files can
use the lighter footprint export.h for this role.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
2011-10-31 19:30:53 -04:00

435 lines
11 KiB
C

/* cpumap.c: used for optimizing CPU assignment
*
* Copyright (C) 2009 Hong H. Pham <hong.pham@windriver.com>
*/
#include <linux/export.h>
#include <linux/slab.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 = cpumask_first(cpu_online_mask);
/* 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:
case SUN4V_CHIP_NIAGARA3:
case SUN4V_CHIP_NIAGARA4:
case SUN4V_CHIP_NIAGARA5:
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 cpumask_first(cpu_online_mask);
}
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);
}