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x86: Merge the x86_32 and x86_64 cpu_idle() functions 

Both functions are mostly identical.
The differences are:

- x86_32's cpu_idle() makes use of check_pgt_cache(), which is a
  nop on both x86_32 and x86_64.

- x86_64's cpu_idle() uses enter/__exit_idle/(), on x86_32 these
  function are a nop.

- In contrast to x86_32, x86_64 calls rcu_idle_enter/exit() in
  the innermost loop because idle notifications need RCU.
  Calling these function on x86_32 also in the innermost loop
  does not hurt.

So we can merge both functions.

Signed-off-by: Richard Weinberger <richard@nod.at>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: paulmck@linux.vnet.ibm.com
Cc: josh@joshtriplett.org
Cc: tj@kernel.org
Link: http://lkml.kernel.org/r/1332709204-22496-1-git-send-email-richard@nod.at
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Richard Weinberger 2012-03-25 23:00:04 +02:00 committed by Ingo Molnar
parent f5243d6de7
commit 90e240142b
4 changed files with 115 additions and 165 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
arch/x86/include/asm/idle.h
View File

@ -14,6 +14,7 @@ void exit_idle(void);
#else /* !CONFIG_X86_64 */
static inline void enter_idle(void) { }
static inline void exit_idle(void) { }
static inline void __exit_idle(void) { }
#endif /* CONFIG_X86_64 */
void amd_e400_remove_cpu(int cpu);

114
arch/x86/kernel/process.c
View File

@ -12,6 +12,9 @@
#include <linux/user-return-notifier.h>
#include <linux/dmi.h>
#include <linux/utsname.h>
#include <linux/stackprotector.h>
#include <linux/tick.h>
#include <linux/cpuidle.h>
#include <trace/events/power.h>
#include <linux/hw_breakpoint.h>
#include <asm/cpu.h>
@ -23,6 +26,24 @@
#include <asm/i387.h>
#include <asm/fpu-internal.h>
#include <asm/debugreg.h>
#include <asm/nmi.h>
#ifdef CONFIG_X86_64
static DEFINE_PER_CPU(unsigned char, is_idle);
static ATOMIC_NOTIFIER_HEAD(idle_notifier);
void idle_notifier_register(struct notifier_block *n)
{
atomic_notifier_chain_register(&idle_notifier, n);
}
EXPORT_SYMBOL_GPL(idle_notifier_register);
void idle_notifier_unregister(struct notifier_block *n)
{
atomic_notifier_chain_unregister(&idle_notifier, n);
}
EXPORT_SYMBOL_GPL(idle_notifier_unregister);
#endif
struct kmem_cache *task_xstate_cachep;
EXPORT_SYMBOL_GPL(task_xstate_cachep);
@ -371,6 +392,99 @@ static inline int hlt_use_halt(void)
}
#endif
#ifndef CONFIG_SMP
static inline void play_dead(void)
{
BUG();
}
#endif
#ifdef CONFIG_X86_64
void enter_idle(void)
{
percpu_write(is_idle, 1);
atomic_notifier_call_chain(&idle_notifier, IDLE_START, NULL);
}
static void __exit_idle(void)
{
if (x86_test_and_clear_bit_percpu(0, is_idle) == 0)
return;
atomic_notifier_call_chain(&idle_notifier, IDLE_END, NULL);
}
/* Called from interrupts to signify idle end */
void exit_idle(void)
{
/* idle loop has pid 0 */
if (current->pid)
return;
__exit_idle();
}
#endif
/*
* The idle thread. There's no useful work to be
* done, so just try to conserve power and have a
* low exit latency (ie sit in a loop waiting for
* somebody to say that they'd like to reschedule)
*/
void cpu_idle(void)
{
/*
* If we're the non-boot CPU, nothing set the stack canary up
* for us. CPU0 already has it initialized but no harm in
* doing it again. This is a good place for updating it, as
* we wont ever return from this function (so the invalid
* canaries already on the stack wont ever trigger).
*/
boot_init_stack_canary();
current_thread_info()->status |= TS_POLLING;
while (1) {
tick_nohz_idle_enter();
while (!need_resched()) {
rmb();
if (cpu_is_offline(smp_processor_id()))
play_dead();
/*
* Idle routines should keep interrupts disabled
* from here on, until they go to idle.
* Otherwise, idle callbacks can misfire.
*/
local_touch_nmi();
local_irq_disable();
enter_idle();
/* Don't trace irqs off for idle */
stop_critical_timings();
/* enter_idle() needs rcu for notifiers */
rcu_idle_enter();
if (cpuidle_idle_call())
pm_idle();
rcu_idle_exit();
start_critical_timings();
/* In many cases the interrupt that ended idle
has already called exit_idle. But some idle
loops can be woken up without interrupt. */
__exit_idle();
}
tick_nohz_idle_exit();
preempt_enable_no_resched();
schedule();
preempt_disable();
}
}
/*
* We use this if we don't have any better
* idle routine..

58
arch/x86/kernel/process_32.c
View File

@ -9,7 +9,6 @@
* This file handles the architecture-dependent parts of process handling..
*/
#include <linux/stackprotector.h>
#include <linux/cpu.h>
#include <linux/errno.h>
#include <linux/sched.h>
@ -31,14 +30,12 @@
#include <linux/kallsyms.h>
#include <linux/ptrace.h>
#include <linux/personality.h>
#include <linux/tick.h>
#include <linux/percpu.h>
#include <linux/prctl.h>
#include <linux/ftrace.h>
#include <linux/uaccess.h>
#include <linux/io.h>
#include <linux/kdebug.h>
#include <linux/cpuidle.h>
#include <asm/pgtable.h>
#include <asm/system.h>
@ -58,7 +55,6 @@
#include <asm/idle.h>
#include <asm/syscalls.h>
#include <asm/debugreg.h>
#include <asm/nmi.h>
asmlinkage void ret_from_fork(void) __asm__("ret_from_fork");
@ -70,60 +66,6 @@ unsigned long thread_saved_pc(struct task_struct *tsk)
return ((unsigned long *)tsk->thread.sp)[3];
}
#ifndef CONFIG_SMP
static inline void play_dead(void)
{
BUG();
}
#endif
/*
* The idle thread. There's no useful work to be
* done, so just try to conserve power and have a
* low exit latency (ie sit in a loop waiting for
* somebody to say that they'd like to reschedule)
*/
void cpu_idle(void)
{
int cpu = smp_processor_id();
/*
* If we're the non-boot CPU, nothing set the stack canary up
* for us. CPU0 already has it initialized but no harm in
* doing it again. This is a good place for updating it, as
* we wont ever return from this function (so the invalid
* canaries already on the stack wont ever trigger).
*/
boot_init_stack_canary();
current_thread_info()->status |= TS_POLLING;
/* endless idle loop with no priority at all */
while (1) {
tick_nohz_idle_enter();
rcu_idle_enter();
while (!need_resched()) {
check_pgt_cache();
rmb();
if (cpu_is_offline(cpu))
play_dead();
local_touch_nmi();
local_irq_disable();
/* Don't trace irqs off for idle */
stop_critical_timings();
if (cpuidle_idle_call())
pm_idle();
start_critical_timings();
}
rcu_idle_exit();
tick_nohz_idle_exit();
schedule_preempt_disabled();
}
}
void __show_regs(struct pt_regs *regs, int all)
{
unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L;

107
arch/x86/kernel/process_64.c
View File

@ -14,7 +14,6 @@
* This file handles the architecture-dependent parts of process handling..
*/
#include <linux/stackprotector.h>
#include <linux/cpu.h>
#include <linux/errno.h>
#include <linux/sched.h>
@ -32,12 +31,10 @@
#include <linux/notifier.h>
#include <linux/kprobes.h>
#include <linux/kdebug.h>
#include <linux/tick.h>
#include <linux/prctl.h>
#include <linux/uaccess.h>
#include <linux/io.h>
#include <linux/ftrace.h>
#include <linux/cpuidle.h>
#include <asm/pgtable.h>
#include <asm/system.h>
@ -52,114 +49,10 @@
#include <asm/idle.h>
#include <asm/syscalls.h>
#include <asm/debugreg.h>
#include <asm/nmi.h>
asmlinkage extern void ret_from_fork(void);
DEFINE_PER_CPU(unsigned long, old_rsp);
static DEFINE_PER_CPU(unsigned char, is_idle);
static ATOMIC_NOTIFIER_HEAD(idle_notifier);
void idle_notifier_register(struct notifier_block *n)
{
atomic_notifier_chain_register(&idle_notifier, n);
}
EXPORT_SYMBOL_GPL(idle_notifier_register);
void idle_notifier_unregister(struct notifier_block *n)
{
atomic_notifier_chain_unregister(&idle_notifier, n);
}
EXPORT_SYMBOL_GPL(idle_notifier_unregister);
void enter_idle(void)
{
percpu_write(is_idle, 1);
atomic_notifier_call_chain(&idle_notifier, IDLE_START, NULL);
}
static void __exit_idle(void)
{
if (x86_test_and_clear_bit_percpu(0, is_idle) == 0)
return;
atomic_notifier_call_chain(&idle_notifier, IDLE_END, NULL);
}
/* Called from interrupts to signify idle end */
void exit_idle(void)
{
/* idle loop has pid 0 */
if (current->pid)
return;
__exit_idle();
}
#ifndef CONFIG_SMP
static inline void play_dead(void)
{
BUG();
}
#endif
/*
* The idle thread. There's no useful work to be
* done, so just try to conserve power and have a
* low exit latency (ie sit in a loop waiting for
* somebody to say that they'd like to reschedule)
*/
void cpu_idle(void)
{
current_thread_info()->status |= TS_POLLING;
/*
* If we're the non-boot CPU, nothing set the stack canary up
* for us. CPU0 already has it initialized but no harm in
* doing it again. This is a good place for updating it, as
* we wont ever return from this function (so the invalid
* canaries already on the stack wont ever trigger).
*/
boot_init_stack_canary();
/* endless idle loop with no priority at all */
while (1) {
tick_nohz_idle_enter();
while (!need_resched()) {
rmb();
if (cpu_is_offline(smp_processor_id()))
play_dead();
/*
* Idle routines should keep interrupts disabled
* from here on, until they go to idle.
* Otherwise, idle callbacks can misfire.
*/
local_touch_nmi();
local_irq_disable();
enter_idle();
/* Don't trace irqs off for idle */
stop_critical_timings();
/* enter_idle() needs rcu for notifiers */
rcu_idle_enter();
if (cpuidle_idle_call())
pm_idle();
rcu_idle_exit();
start_critical_timings();
/* In many cases the interrupt that ended idle
has already called exit_idle. But some idle
loops can be woken up without interrupt. */
__exit_idle();
}
tick_nohz_idle_exit();
schedule_preempt_disabled();
}
}
/* Prints also some state that isn't saved in the pt_regs */
void __show_regs(struct pt_regs *regs, int all)