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s390/nohz: use a per-cpu flag for arch_needs_cpu

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Move the nohz_delay bit from the s390_idle data structure to the
per-cpu flags. Clear the nohz delay flag in __cpu_disable and
remove the cpu hotplug notifier that used to do this.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Martin Schwidefsky 2014-09-30 17:37:52 +02:00
parent a9b1649917
commit fe0f49768d
9 changed files with 11 additions and 31 deletions
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8
arch/s390/include/asm/cputime.h
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@ -166,7 +166,6 @@ static inline clock_t cputime64_to_clock_t(cputime64_t cputime)
}
struct s390_idle_data {
int nohz_delay;
unsigned int sequence;
unsigned long long idle_count;
unsigned long long idle_time;
@ -182,11 +181,4 @@ cputime64_t s390_get_idle_time(int cpu);
#define arch_idle_time(cpu) s390_get_idle_time(cpu)
static inline int s390_nohz_delay(int cpu)
{
return __get_cpu_var(s390_idle).nohz_delay != 0;
}
#define arch_needs_cpu(cpu) s390_nohz_delay(cpu)
#endif /* _S390_CPUTIME_H */

4
arch/s390/include/asm/processor.h
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@ -13,9 +13,11 @@
#define CIF_MCCK_PENDING 0 /* machine check handling is pending */
#define CIF_ASCE 1 /* user asce needs fixup / uaccess */
#define CIF_NOHZ_DELAY 2 /* delay HZ disable for a tick */
#define _CIF_MCCK_PENDING (1<<CIF_MCCK_PENDING)
#define _CIF_ASCE (1<<CIF_ASCE)
#define _CIF_NOHZ_DELAY (1<<CIF_NOHZ_DELAY)
#ifndef __ASSEMBLY__
@ -43,6 +45,8 @@ static inline int test_cpu_flag(int flag)
return !!(S390_lowcore.cpu_flags & (1U << flag));
}
#define arch_needs_cpu() test_cpu_flag(CIF_NOHZ_DELAY)
/*
* Default implementation of macro that returns current
* instruction pointer ("program counter").

2
arch/s390/kernel/irq.c
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@ -259,7 +259,7 @@ static irqreturn_t do_ext_interrupt(int irq, void *dummy)
ext_code = *(struct ext_code *) &regs->int_code;
if (ext_code.code != EXT_IRQ_CLK_COMP)
__get_cpu_var(s390_idle).nohz_delay = 1;
set_cpu_flag(CIF_NOHZ_DELAY);
index = ext_hash(ext_code.code);
rcu_read_lock();

1
arch/s390/kernel/smp.c
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@ -720,6 +720,7 @@ int __cpu_disable(void)
cregs[6] &= ~0xff000000UL; /* disable all I/O interrupts */
cregs[14] &= ~0x1f000000UL; /* disable most machine checks */
__ctl_load(cregs, 0, 15);
clear_cpu_flag(CIF_NOHZ_DELAY);
return 0;
}

19
arch/s390/kernel/vtime.c
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@ -163,7 +163,7 @@ void __kprobes vtime_stop_cpu(void)
/* Wait for external, I/O or machine check interrupt. */
psw_mask = PSW_KERNEL_BITS | PSW_MASK_WAIT | PSW_MASK_DAT |
PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK;
idle->nohz_delay = 0;
clear_cpu_flag(CIF_NOHZ_DELAY);
/* Call the assembler magic in entry.S */
psw_idle(idle, psw_mask);
@ -378,25 +378,8 @@ void init_cpu_vtimer(void)
set_vtimer(VTIMER_MAX_SLICE);
}
static int s390_nohz_notify(struct notifier_block *self, unsigned long action,
void *hcpu)
{
struct s390_idle_data *idle;
long cpu = (long) hcpu;
idle = &per_cpu(s390_idle, cpu);
switch (action & ~CPU_TASKS_FROZEN) {
case CPU_DYING:
idle->nohz_delay = 0;
default:
break;
}
return NOTIFY_OK;
}
void __init vtime_init(void)
{
/* Enable cpu timer interrupts on the boot cpu. */
init_cpu_vtimer();
cpu_notifier(s390_nohz_notify, 0);
}

2
drivers/s390/cio/airq.c
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@ -87,7 +87,7 @@ static irqreturn_t do_airq_interrupt(int irq, void *dummy)
struct airq_struct *airq;
struct hlist_head *head;
__this_cpu_write(s390_idle.nohz_delay, 1);
set_cpu_flag(CIF_NOHZ_DELAY);
tpi_info = (struct tpi_info *) &get_irq_regs()->int_code;
head = &airq_lists[tpi_info->isc];
rcu_read_lock();

2
drivers/s390/cio/cio.c
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@ -561,7 +561,7 @@ static irqreturn_t do_cio_interrupt(int irq, void *dummy)
struct subchannel *sch;
struct irb *irb;
__this_cpu_write(s390_idle.nohz_delay, 1);
set_cpu_flag(CIF_NOHZ_DELAY);
tpi_info = (struct tpi_info *) &get_irq_regs()->int_code;
irb = &__get_cpu_var(cio_irb);
sch = (struct subchannel *)(unsigned long) tpi_info->intparm;

2
include/linux/tick.h
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@ -108,7 +108,7 @@ extern struct tick_sched *tick_get_tick_sched(int cpu);
extern void tick_irq_enter(void);
extern int tick_oneshot_mode_active(void);
# ifndef arch_needs_cpu
# define arch_needs_cpu(cpu) (0)
# define arch_needs_cpu() (0)
# endif
# else
static inline void tick_clock_notify(void) { }

2
kernel/time/tick-sched.c
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@ -572,7 +572,7 @@ static ktime_t tick_nohz_stop_sched_tick(struct tick_sched *ts,
} while (read_seqretry(&jiffies_lock, seq));
if (rcu_needs_cpu(cpu, &rcu_delta_jiffies) ||
arch_needs_cpu(cpu) || irq_work_needs_cpu()) {
arch_needs_cpu() || irq_work_needs_cpu()) {
next_jiffies = last_jiffies + 1;
delta_jiffies = 1;
} else {