diff options
| -rw-r--r-- | Documentation/x86_64/boot-options.txt | 3 | ||||
| -rw-r--r-- | arch/x86_64/kernel/mpparse.c | 8 | ||||
| -rw-r--r-- | arch/x86_64/kernel/smpboot.c | 39 | ||||
| -rw-r--r-- | include/asm-x86_64/smp.h | 2 |
4 files changed, 47 insertions, 5 deletions
diff --git a/Documentation/x86_64/boot-options.txt b/Documentation/x86_64/boot-options.txt index ffe1c062088..a83139692cd 100644 --- a/Documentation/x86_64/boot-options.txt +++ b/Documentation/x86_64/boot-options.txt @@ -122,6 +122,9 @@ SMP cpumask=MASK only use cpus with bits set in mask + additional_cpus=NUM Allow NUM more CPUs for hotplug + (defaults are specified by the BIOS or half the available CPUs) + NUMA numa=off Only set up a single NUMA node spanning all memory. diff --git a/arch/x86_64/kernel/mpparse.c b/arch/x86_64/kernel/mpparse.c index 4a581d1cefb..1d61f10a92c 100644 --- a/arch/x86_64/kernel/mpparse.c +++ b/arch/x86_64/kernel/mpparse.c @@ -65,7 +65,9 @@ unsigned long mp_lapic_addr = 0; /* Processor that is doing the boot up */ unsigned int boot_cpu_id = -1U; /* Internal processor count */ -static unsigned int num_processors = 0; +unsigned int num_processors __initdata = 0; + +unsigned disabled_cpus __initdata; /* Bitmask of physically existing CPUs */ physid_mask_t phys_cpu_present_map = PHYSID_MASK_NONE; @@ -109,8 +111,10 @@ static void __init MP_processor_info (struct mpc_config_processor *m) int ver, cpu; static int found_bsp=0; - if (!(m->mpc_cpuflag & CPU_ENABLED)) + if (!(m->mpc_cpuflag & CPU_ENABLED)) { + disabled_cpus++; return; + } printk(KERN_INFO "Processor #%d %d:%d APIC version %d\n", m->mpc_apicid, diff --git a/arch/x86_64/kernel/smpboot.c b/arch/x86_64/kernel/smpboot.c index 3393fc08823..f74319a8065 100644 --- a/arch/x86_64/kernel/smpboot.c +++ b/arch/x86_64/kernel/smpboot.c @@ -880,6 +880,9 @@ static __init void disable_smp(void) } #ifdef CONFIG_HOTPLUG_CPU + +int additional_cpus __initdata = -1; + /* * cpu_possible_map should be static, it cannot change as cpu's * are onlined, or offlined. The reason is per-cpu data-structures @@ -888,14 +891,38 @@ static __init void disable_smp(void) * 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. - * If cpu-hotplug is supported, then we need to preallocate for all - * those NR_CPUS, hence cpu_possible_map represents entire NR_CPUS range. * - Ashok Raj + * + * Three ways to find out the number of additional hotplug CPUs: + * - If the BIOS specified disabled CPUs in ACPI/mptables use that. + * - otherwise use half of the available CPUs or 2, whatever is more. + * - The user can overwrite it with additional_cpus=NUM + * We do this because additional CPUs waste a lot of memory. + * -AK */ __init void prefill_possible_map(void) { int i; - for (i = 0; i < NR_CPUS; i++) + int possible; + + if (additional_cpus == -1) { + if (disabled_cpus > 0) { + additional_cpus = disabled_cpus; + } else { + additional_cpus = num_processors / 2; + if (additional_cpus == 0) + additional_cpus = 2; + } + } + possible = num_processors + additional_cpus; + if (possible > NR_CPUS) + possible = NR_CPUS; + + printk(KERN_INFO "SMP: Allowing %d CPUs, %d hotplug CPUs\n", + possible, + max_t(int, possible - num_processors, 0)); + + for (i = 0; i < possible; i++) cpu_set(i, cpu_possible_map); } #endif @@ -1151,6 +1178,12 @@ void __cpu_die(unsigned int cpu) printk(KERN_ERR "CPU %u didn't die...\n", cpu); } +static __init int setup_additional_cpus(char *s) +{ + return get_option(&s, &additional_cpus); +} +__setup("additional_cpus=", setup_additional_cpus); + #else /* ... !CONFIG_HOTPLUG_CPU */ int __cpu_disable(void) diff --git a/include/asm-x86_64/smp.h b/include/asm-x86_64/smp.h index 592161e979e..cf8f969f902 100644 --- a/include/asm-x86_64/smp.h +++ b/include/asm-x86_64/smp.h @@ -81,6 +81,8 @@ extern int safe_smp_processor_id(void); extern int __cpu_disable(void); extern void __cpu_die(unsigned int cpu); extern void prefill_possible_map(void); +extern unsigned num_processors; +extern unsigned disabled_cpus; #endif /* !ASSEMBLY */ |