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s390/smp: improve setup of possible cpu mask

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Since under z/VM we cannot have more than 64 cpus, make sure the
cpu_possible_mask does not contain more bits.
This avoids wasting memory for dynamic per-cpu allocations if
CONFIG_NR_CPUS is larger than 64.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Heiko Carstens 2013-12-16 14:31:26 +01:00 committed by Martin Schwidefsky
parent 319e2e3f63
commit d80512f874
4 changed files with 19 additions and 10 deletions
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1
arch/s390/Kconfig
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@ -135,7 +135,6 @@ config S390
select HAVE_SYSCALL_TRACEPOINTS
select HAVE_UID16 if 32BIT
select HAVE_VIRT_CPU_ACCOUNTING
select INIT_ALL_POSSIBLE
select KTIME_SCALAR if 32BIT
select MODULES_USE_ELF_RELA
select OLD_SIGACTION

2
arch/s390/include/asm/smp.h
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@ -31,6 +31,7 @@ extern void smp_yield(void);
extern void smp_stop_cpu(void);
extern void smp_cpu_set_polarization(int cpu, int val);
extern int smp_cpu_get_polarization(int cpu);
extern void smp_fill_possible_mask(void);
#else /* CONFIG_SMP */
@ -50,6 +51,7 @@ static inline int smp_vcpu_scheduled(int cpu) { return 1; }
static inline void smp_yield_cpu(int cpu) { }
static inline void smp_yield(void) { }
static inline void smp_stop_cpu(void) { }
static inline void smp_fill_possible_mask(void) { }
#endif /* CONFIG_SMP */

1
arch/s390/kernel/setup.c
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@ -1023,6 +1023,7 @@ void __init setup_arch(char **cmdline_p)
setup_vmcoreinfo();
setup_lowcore();
smp_fill_possible_mask();
cpu_init();
s390_init_cpu_topology();

25
arch/s390/kernel/smp.c
View File

@ -721,18 +721,14 @@ int __cpu_up(unsigned int cpu, struct task_struct *tidle)
return 0;
}
static int __init setup_possible_cpus(char *s)
{
int max, cpu;
static unsigned int setup_possible_cpus __initdata;
if (kstrtoint(s, 0, &max) < 0)
return 0;
init_cpu_possible(cpumask_of(0));
for (cpu = 1; cpu < max && cpu < nr_cpu_ids; cpu++)
set_cpu_possible(cpu, true);
static int __init _setup_possible_cpus(char *s)
{
get_option(&s, &setup_possible_cpus);
return 0;
}
early_param("possible_cpus", setup_possible_cpus);
early_param("possible_cpus", _setup_possible_cpus);
#ifdef CONFIG_HOTPLUG_CPU
@ -775,6 +771,17 @@ void __noreturn cpu_die(void)
#endif /* CONFIG_HOTPLUG_CPU */
void __init smp_fill_possible_mask(void)
{
unsigned int possible, cpu;
possible = setup_possible_cpus;
if (!possible)
possible = MACHINE_IS_VM ? 64 : nr_cpu_ids;
for (cpu = 0; cpu < possible && cpu < nr_cpu_ids; cpu++)
set_cpu_possible(cpu, true);
}
void __init smp_prepare_cpus(unsigned int max_cpus)
{
/* request the 0x1201 emergency signal external interrupt */