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Subject[patch 1/6] x86: simplify idle selection
default_idle is selected in cpu_idle(), when no other idle routine is
selected. Select it in select_idle_routine() when mwait is not
selected.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andreas Herrmann <andreas.herrmann3@amd.com>

---
arch/x86/kernel/process.c | 18 +++++++-----------
arch/x86/kernel/process_32.c | 7 +------
arch/x86/kernel/process_64.c | 7 ++-----
3 files changed, 10 insertions(+), 22 deletions(-)
Index: linux-2.6/arch/x86/kernel/process.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/process.c
+++ linux-2.6/arch/x86/kernel/process.c
@@ -139,27 +139,23 @@ static int __cpuinit mwait_usable(const

void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c)
{
- static int selected;
-
- if (selected)
- return;
#ifdef CONFIG_X86_SMP
if (pm_idle == poll_idle && smp_num_siblings > 1) {
printk(KERN_WARNING "WARNING: polling idle and HT enabled,"
" performance may degrade.\n");
}
#endif
+ if (pm_idle)
+ return;
+
if (cpu_has(c, X86_FEATURE_MWAIT) && mwait_usable(c)) {
/*
- * Skip, if setup has overridden idle.
* One CPU supports mwait => All CPUs supports mwait
*/
- if (!pm_idle) {
- printk(KERN_INFO "using mwait in idle threads.\n");
- pm_idle = mwait_idle;
- }
- }
- selected = 1;
+ printk(KERN_INFO "using mwait in idle threads.\n");
+ pm_idle = mwait_idle;
+ } else
+ pm_idle = default_idle;
}

static int __init idle_setup(char *str)
Index: linux-2.6/arch/x86/kernel/process_32.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/process_32.c
+++ linux-2.6/arch/x86/kernel/process_32.c
@@ -168,24 +168,19 @@ void cpu_idle(void)
while (1) {
tick_nohz_stop_sched_tick();
while (!need_resched()) {
- void (*idle)(void);

check_pgt_cache();
rmb();
- idle = pm_idle;

if (rcu_pending(cpu))
rcu_check_callbacks(cpu, 0);

- if (!idle)
- idle = default_idle;
-
if (cpu_is_offline(cpu))
play_dead();

local_irq_disable();
__get_cpu_var(irq_stat).idle_timestamp = jiffies;
- idle();
+ pm_idle();
}
tick_nohz_restart_sched_tick();
preempt_enable_no_resched();
Index: linux-2.6/arch/x86/kernel/process_64.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/process_64.c
+++ linux-2.6/arch/x86/kernel/process_64.c
@@ -150,12 +150,9 @@ void cpu_idle(void)
while (1) {
tick_nohz_stop_sched_tick();
while (!need_resched()) {
- void (*idle)(void);

rmb();
- idle = pm_idle;
- if (!idle)
- idle = default_idle;
+
if (cpu_is_offline(smp_processor_id()))
play_dead();
/*
@@ -165,7 +162,7 @@ void cpu_idle(void)
*/
local_irq_disable();
enter_idle();
- idle();
+ pm_idle();
/* In many cases the interrupt that ended idle
has already called exit_idle. But some idle
loops can be woken up without interrupt. */
--



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