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[IA64] Count disabled cpus as potential hot-pluggable CPUs

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Have a facility to account for potentially hot-pluggable CPUs. ACPI doesnt
give a determinstic method to find hot-pluggable CPUs. Hence we use 2 methods
to assist.

- BIOS can mark potentially hot-pluggable CPUs as disabled in the MADT tables.
- User can specify the number of hot-pluggable CPUs via parameter
  additional_cpus=X

The option is enabled only if ACPI_CONFIG_HOTPLUG_CPU=y which enables the
physical hotplug option. Without which user can still use logical onlining
and offlining of CPUs by enabling CONFIG_HOTPLUG_CPU=y

Adds more bits to cpu_possible_map for potentially hot-pluggable cpus.

Signed-off-by: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
This commit is contained in:
Ashok Raj 2006-02-14 15:01:12 -08:00 committed by Tony Luck
parent 69aa234b91
commit a6b14fa6fd
3 changed files with 62 additions and 0 deletions
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56
arch/ia64/kernel/acpi.c
View file

@ -761,6 +761,62 @@ int acpi_map_cpu2node(acpi_handle handle, int cpu, long physid)
return (0);
}
int additional_cpus __initdata = -1;
static __init int setup_additional_cpus(char *s)
{
if (s)
additional_cpus = simple_strtol(s, NULL, 0);
return 0;
}
early_param("additional_cpus", setup_additional_cpus);
/*
* cpu_possible_map should be static, it cannot change as cpu's
* are onlined, or offlined. The reason is per-cpu data-structures
* are allocated by some modules at init time, and dont expect to
* do this dynamically on cpu arrival/departure.
* cpu_present_map on the other hand can change dynamically.
* In case when cpu_hotplug is not compiled, then we resort to current
* behaviour, which is cpu_possible == cpu_present.
* - Ashok Raj
*
* Three ways to find out the number of additional hotplug CPUs:
* - If the BIOS specified disabled CPUs in ACPI/mptables use that.
* - The user can overwrite it with additional_cpus=NUM
* - Otherwise don't reserve additional CPUs.
*/
__init void prefill_possible_map(void)
{
int i;
int possible, disabled_cpus;
disabled_cpus = total_cpus - available_cpus;
if (additional_cpus == -1) {
if (disabled_cpus > 0) {
possible = total_cpus;
additional_cpus = disabled_cpus;
}
else {
possible = available_cpus;
additional_cpus = 0;
}
} else {
possible = available_cpus + additional_cpus;
}
if (possible > NR_CPUS)
possible = NR_CPUS;
printk(KERN_INFO "SMP: Allowing %d CPUs, %d hotplug CPUs\n",
possible,
max_t(int, additional_cpus, 0));
for (i = 0; i < possible; i++)
cpu_set(i, cpu_possible_map);
}
int acpi_map_lsapic(acpi_handle handle, int *pcpu)
{
struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };

4
arch/ia64/kernel/setup.c
View file

@ -430,6 +430,7 @@ setup_arch (char **cmdline_p)
if (early_console_setup(*cmdline_p) == 0)
mark_bsp_online();
parse_early_param();
#ifdef CONFIG_ACPI
/* Initialize the ACPI boot-time table parser */
acpi_table_init();
@ -688,6 +689,9 @@ void
setup_per_cpu_areas (void)
{
/* start_kernel() requires this... */
#ifdef CONFIG_ACPI_HOTPLUG_CPU
prefill_possible_map();
#endif
}
/*

2
include/asm-ia64/acpi.h
View file

@ -106,6 +106,8 @@ extern unsigned int can_cpei_retarget(void);
extern unsigned int is_cpu_cpei_target(unsigned int cpu);
extern void set_cpei_target_cpu(unsigned int cpu);
extern unsigned int get_cpei_target_cpu(void);
extern void prefill_possible_map(void);
extern int additional_cpus;
#ifdef CONFIG_ACPI_NUMA
/* Proximity bitmap length; _PXM is at most 255 (8 bit)*/