android_kernel_motorola_sm6225/arch/x86/kernel/setup_percpu.c
Linus Torvalds e56b3bc794 cpu masks: optimize and clean up cpumask_of_cpu()
Clean up and optimize cpumask_of_cpu(), by sharing all the zero words.

Instead of stupidly generating all possible i=0...NR_CPUS 2^i patterns
creating a huge array of constant bitmasks, realize that the zero words
can be shared.

In other words, on a 64-bit architecture, we only ever need 64 of these
arrays - with a different bit set in one single world (with enough zero
words around it so that we can create any bitmask by just offsetting in
that big array). And then we just put enough zeroes around it that we
can point every single cpumask to be one of those things.

So when we have 4k CPU's, instead of having 4k arrays (of 4k bits each,
with one bit set in each array - 2MB memory total), we have exactly 64
arrays instead, each 8k bits in size (64kB total).

And then we just point cpumask(n) to the right position (which we can
calculate dynamically). Once we have the right arrays, getting
"cpumask(n)" ends up being:

  static inline const cpumask_t *get_cpu_mask(unsigned int cpu)
  {
          const unsigned long *p = cpu_bit_bitmap[1 + cpu % BITS_PER_LONG];
          p -= cpu / BITS_PER_LONG;
          return (const cpumask_t *)p;
  }

This brings other advantages and simplifications as well:

 - we are not wasting memory that is just filled with a single bit in
   various different places

 - we don't need all those games to re-create the arrays in some dense
   format, because they're already going to be dense enough.

if we compile a kernel for up to 4k CPU's, "wasting" that 64kB of memory
is a non-issue (especially since by doing this "overlapping" trick we
probably get better cache behaviour anyway).

[ mingo@elte.hu:

  Converted Linus's mails into a commit. See:

     http://lkml.org/lkml/2008/7/27/156
     http://lkml.org/lkml/2008/7/28/320

  Also applied a family filter - which also has the side-effect of leaving
  out the bits where Linus calls me an idio... Oh, never mind ;-)
]

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Mike Travis <travis@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-07-28 22:20:41 +02:00

378 lines
9 KiB
C

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/bootmem.h>
#include <linux/percpu.h>
#include <linux/kexec.h>
#include <linux/crash_dump.h>
#include <asm/smp.h>
#include <asm/percpu.h>
#include <asm/sections.h>
#include <asm/processor.h>
#include <asm/setup.h>
#include <asm/topology.h>
#include <asm/mpspec.h>
#include <asm/apicdef.h>
#include <asm/highmem.h>
#ifdef CONFIG_X86_LOCAL_APIC
unsigned int num_processors;
unsigned disabled_cpus __cpuinitdata;
/* Processor that is doing the boot up */
unsigned int boot_cpu_physical_apicid = -1U;
unsigned int max_physical_apicid;
EXPORT_SYMBOL(boot_cpu_physical_apicid);
/* Bitmask of physically existing CPUs */
physid_mask_t phys_cpu_present_map;
#endif
/* map cpu index to physical APIC ID */
DEFINE_EARLY_PER_CPU(u16, x86_cpu_to_apicid, BAD_APICID);
DEFINE_EARLY_PER_CPU(u16, x86_bios_cpu_apicid, BAD_APICID);
EXPORT_EARLY_PER_CPU_SYMBOL(x86_cpu_to_apicid);
EXPORT_EARLY_PER_CPU_SYMBOL(x86_bios_cpu_apicid);
#if defined(CONFIG_NUMA) && defined(CONFIG_X86_64)
#define X86_64_NUMA 1
/* map cpu index to node index */
DEFINE_EARLY_PER_CPU(int, x86_cpu_to_node_map, NUMA_NO_NODE);
EXPORT_EARLY_PER_CPU_SYMBOL(x86_cpu_to_node_map);
/* which logical CPUs are on which nodes */
cpumask_t *node_to_cpumask_map;
EXPORT_SYMBOL(node_to_cpumask_map);
/* setup node_to_cpumask_map */
static void __init setup_node_to_cpumask_map(void);
#else
static inline void setup_node_to_cpumask_map(void) { }
#endif
#if defined(CONFIG_HAVE_SETUP_PER_CPU_AREA) && defined(CONFIG_X86_SMP)
/*
* Copy data used in early init routines from the initial arrays to the
* per cpu data areas. These arrays then become expendable and the
* *_early_ptr's are zeroed indicating that the static arrays are gone.
*/
static void __init setup_per_cpu_maps(void)
{
int cpu;
for_each_possible_cpu(cpu) {
per_cpu(x86_cpu_to_apicid, cpu) =
early_per_cpu_map(x86_cpu_to_apicid, cpu);
per_cpu(x86_bios_cpu_apicid, cpu) =
early_per_cpu_map(x86_bios_cpu_apicid, cpu);
#ifdef X86_64_NUMA
per_cpu(x86_cpu_to_node_map, cpu) =
early_per_cpu_map(x86_cpu_to_node_map, cpu);
#endif
}
/* indicate the early static arrays will soon be gone */
early_per_cpu_ptr(x86_cpu_to_apicid) = NULL;
early_per_cpu_ptr(x86_bios_cpu_apicid) = NULL;
#ifdef X86_64_NUMA
early_per_cpu_ptr(x86_cpu_to_node_map) = NULL;
#endif
}
#ifdef CONFIG_X86_32
/*
* Great future not-so-futuristic plan: make i386 and x86_64 do it
* the same way
*/
unsigned long __per_cpu_offset[NR_CPUS] __read_mostly;
EXPORT_SYMBOL(__per_cpu_offset);
static inline void setup_cpu_pda_map(void) { }
#elif !defined(CONFIG_SMP)
static inline void setup_cpu_pda_map(void) { }
#else /* CONFIG_SMP && CONFIG_X86_64 */
/*
* Allocate cpu_pda pointer table and array via alloc_bootmem.
*/
static void __init setup_cpu_pda_map(void)
{
char *pda;
struct x8664_pda **new_cpu_pda;
unsigned long size;
int cpu;
size = roundup(sizeof(struct x8664_pda), cache_line_size());
/* allocate cpu_pda array and pointer table */
{
unsigned long tsize = nr_cpu_ids * sizeof(void *);
unsigned long asize = size * (nr_cpu_ids - 1);
tsize = roundup(tsize, cache_line_size());
new_cpu_pda = alloc_bootmem(tsize + asize);
pda = (char *)new_cpu_pda + tsize;
}
/* initialize pointer table to static pda's */
for_each_possible_cpu(cpu) {
if (cpu == 0) {
/* leave boot cpu pda in place */
new_cpu_pda[0] = cpu_pda(0);
continue;
}
new_cpu_pda[cpu] = (struct x8664_pda *)pda;
new_cpu_pda[cpu]->in_bootmem = 1;
pda += size;
}
/* point to new pointer table */
_cpu_pda = new_cpu_pda;
}
#endif
/*
* Great future plan:
* Declare PDA itself and support (irqstack,tss,pgd) as per cpu data.
* Always point %gs to its beginning
*/
void __init setup_per_cpu_areas(void)
{
ssize_t size = PERCPU_ENOUGH_ROOM;
char *ptr;
int cpu;
/* Setup cpu_pda map */
setup_cpu_pda_map();
/* Copy section for each CPU (we discard the original) */
size = PERCPU_ENOUGH_ROOM;
printk(KERN_INFO "PERCPU: Allocating %zd bytes of per cpu data\n",
size);
for_each_possible_cpu(cpu) {
#ifndef CONFIG_NEED_MULTIPLE_NODES
ptr = alloc_bootmem_pages(size);
#else
int node = early_cpu_to_node(cpu);
if (!node_online(node) || !NODE_DATA(node)) {
ptr = alloc_bootmem_pages(size);
printk(KERN_INFO
"cpu %d has no node %d or node-local memory\n",
cpu, node);
}
else
ptr = alloc_bootmem_pages_node(NODE_DATA(node), size);
#endif
per_cpu_offset(cpu) = ptr - __per_cpu_start;
memcpy(ptr, __per_cpu_start, __per_cpu_end - __per_cpu_start);
}
printk(KERN_DEBUG "NR_CPUS: %d, nr_cpu_ids: %d, nr_node_ids %d\n",
NR_CPUS, nr_cpu_ids, nr_node_ids);
/* Setup percpu data maps */
setup_per_cpu_maps();
/* Setup node to cpumask map */
setup_node_to_cpumask_map();
}
#endif
#ifdef X86_64_NUMA
/*
* Allocate node_to_cpumask_map based on number of available nodes
* Requires node_possible_map to be valid.
*
* Note: node_to_cpumask() is not valid until after this is done.
*/
static void __init setup_node_to_cpumask_map(void)
{
unsigned int node, num = 0;
cpumask_t *map;
/* setup nr_node_ids if not done yet */
if (nr_node_ids == MAX_NUMNODES) {
for_each_node_mask(node, node_possible_map)
num = node;
nr_node_ids = num + 1;
}
/* allocate the map */
map = alloc_bootmem_low(nr_node_ids * sizeof(cpumask_t));
pr_debug(KERN_DEBUG "Node to cpumask map at %p for %d nodes\n",
map, nr_node_ids);
/* node_to_cpumask() will now work */
node_to_cpumask_map = map;
}
void __cpuinit numa_set_node(int cpu, int node)
{
int *cpu_to_node_map = early_per_cpu_ptr(x86_cpu_to_node_map);
if (cpu_pda(cpu) && node != NUMA_NO_NODE)
cpu_pda(cpu)->nodenumber = node;
if (cpu_to_node_map)
cpu_to_node_map[cpu] = node;
else if (per_cpu_offset(cpu))
per_cpu(x86_cpu_to_node_map, cpu) = node;
else
pr_debug("Setting node for non-present cpu %d\n", cpu);
}
void __cpuinit numa_clear_node(int cpu)
{
numa_set_node(cpu, NUMA_NO_NODE);
}
#ifndef CONFIG_DEBUG_PER_CPU_MAPS
void __cpuinit numa_add_cpu(int cpu)
{
cpu_set(cpu, node_to_cpumask_map[early_cpu_to_node(cpu)]);
}
void __cpuinit numa_remove_cpu(int cpu)
{
cpu_clear(cpu, node_to_cpumask_map[cpu_to_node(cpu)]);
}
#else /* CONFIG_DEBUG_PER_CPU_MAPS */
/*
* --------- debug versions of the numa functions ---------
*/
static void __cpuinit numa_set_cpumask(int cpu, int enable)
{
int node = cpu_to_node(cpu);
cpumask_t *mask;
char buf[64];
if (node_to_cpumask_map == NULL) {
printk(KERN_ERR "node_to_cpumask_map NULL\n");
dump_stack();
return;
}
mask = &node_to_cpumask_map[node];
if (enable)
cpu_set(cpu, *mask);
else
cpu_clear(cpu, *mask);
cpulist_scnprintf(buf, sizeof(buf), *mask);
printk(KERN_DEBUG "%s cpu %d node %d: mask now %s\n",
enable? "numa_add_cpu":"numa_remove_cpu", cpu, node, buf);
}
void __cpuinit numa_add_cpu(int cpu)
{
numa_set_cpumask(cpu, 1);
}
void __cpuinit numa_remove_cpu(int cpu)
{
numa_set_cpumask(cpu, 0);
}
int cpu_to_node(int cpu)
{
if (early_per_cpu_ptr(x86_cpu_to_node_map)) {
printk(KERN_WARNING
"cpu_to_node(%d): usage too early!\n", cpu);
dump_stack();
return early_per_cpu_ptr(x86_cpu_to_node_map)[cpu];
}
return per_cpu(x86_cpu_to_node_map, cpu);
}
EXPORT_SYMBOL(cpu_to_node);
/*
* Same function as cpu_to_node() but used if called before the
* per_cpu areas are setup.
*/
int early_cpu_to_node(int cpu)
{
if (early_per_cpu_ptr(x86_cpu_to_node_map))
return early_per_cpu_ptr(x86_cpu_to_node_map)[cpu];
if (!per_cpu_offset(cpu)) {
printk(KERN_WARNING
"early_cpu_to_node(%d): no per_cpu area!\n", cpu);
dump_stack();
return NUMA_NO_NODE;
}
return per_cpu(x86_cpu_to_node_map, cpu);
}
/* empty cpumask */
static const cpumask_t cpu_mask_none;
/*
* Returns a pointer to the bitmask of CPUs on Node 'node'.
*/
const cpumask_t *_node_to_cpumask_ptr(int node)
{
if (node_to_cpumask_map == NULL) {
printk(KERN_WARNING
"_node_to_cpumask_ptr(%d): no node_to_cpumask_map!\n",
node);
dump_stack();
return (const cpumask_t *)&cpu_online_map;
}
if (node >= nr_node_ids) {
printk(KERN_WARNING
"_node_to_cpumask_ptr(%d): node > nr_node_ids(%d)\n",
node, nr_node_ids);
dump_stack();
return &cpu_mask_none;
}
return &node_to_cpumask_map[node];
}
EXPORT_SYMBOL(_node_to_cpumask_ptr);
/*
* Returns a bitmask of CPUs on Node 'node'.
*
* Side note: this function creates the returned cpumask on the stack
* so with a high NR_CPUS count, excessive stack space is used. The
* node_to_cpumask_ptr function should be used whenever possible.
*/
cpumask_t node_to_cpumask(int node)
{
if (node_to_cpumask_map == NULL) {
printk(KERN_WARNING
"node_to_cpumask(%d): no node_to_cpumask_map!\n", node);
dump_stack();
return cpu_online_map;
}
if (node >= nr_node_ids) {
printk(KERN_WARNING
"node_to_cpumask(%d): node > nr_node_ids(%d)\n",
node, nr_node_ids);
dump_stack();
return cpu_mask_none;
}
return node_to_cpumask_map[node];
}
EXPORT_SYMBOL(node_to_cpumask);
/*
* --------- end of debug versions of the numa functions ---------
*/
#endif /* CONFIG_DEBUG_PER_CPU_MAPS */
#endif /* X86_64_NUMA */