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[PATCH] x86: Don't use nested idle loops

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Currently the idle loop has two nested loops -- one high level
in cpu_idle and in some low level idle functions another one.

Looping in the low level idle functions breaks the idle notifiers
because interrupts waking up sleep states need to execute
exit_idle() which is only in cpu_idle().

So don't do that, only loop in cpu_idle(). This only removes
code.

In some cases e.g. poll_idle the idle loop is a little longer
now because cpu_idle checks more things. I hope that isn't a problem
ACPI idle doesn't change behaviour because it never looped anyways.

Cc: len.brown@intel.com
Cc: eranian@hpl.hp.com
Signed-off-by: Andi Kleen <ak@suse.de>
This commit is contained in:
Andi Kleen 2006-12-07 02:14:03 +01:00 committed by Andi Kleen
parent 63cb683c6e
commit 72690a2118
2 changed files with 18 additions and 42 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

30
arch/i386/kernel/process.c
View File

@ -100,22 +100,18 @@ EXPORT_SYMBOL(enable_hlt);
*/
void default_idle(void)
{
local_irq_enable();
if (!hlt_counter && boot_cpu_data.hlt_works_ok) {
current_thread_info()->status &= ~TS_POLLING;
smp_mb__after_clear_bit();
while (!need_resched()) {
local_irq_disable();
if (!need_resched())
safe_halt();
else
local_irq_enable();
}
local_irq_disable();
if (!need_resched())
safe_halt(); /* enables interrupts racelessly */
else
local_irq_enable();
current_thread_info()->status |= TS_POLLING;
} else {
while (!need_resched())
cpu_relax();
/* loop is done by the caller */
cpu_relax();
}
}
#ifdef CONFIG_APM_MODULE
@ -129,14 +125,7 @@ EXPORT_SYMBOL(default_idle);
*/
static void poll_idle (void)
{
local_irq_enable();
asm volatile(
"2:"
"testl %0, %1;"
"rep; nop;"
"je 2b;"
: : "i"(_TIF_NEED_RESCHED), "m" (current_thread_info()->flags));
cpu_relax();
}
#ifdef CONFIG_HOTPLUG_CPU
@ -257,8 +246,7 @@ void mwait_idle_with_hints(unsigned long eax, unsigned long ecx)
static void mwait_idle(void)
{
local_irq_enable();
while (!need_resched())
mwait_idle_with_hints(0, 0);
mwait_idle_with_hints(0, 0);
}
void __devinit select_idle_routine(const struct cpuinfo_x86 *c)

30
arch/x86_64/kernel/process.c
View File

@ -108,17 +108,15 @@ void exit_idle(void)
*/
static void default_idle(void)
{
local_irq_enable();
current_thread_info()->status &= ~TS_POLLING;
smp_mb__after_clear_bit();
while (!need_resched()) {
local_irq_disable();
if (!need_resched())
safe_halt();
else
local_irq_enable();
}
local_irq_disable();
if (!need_resched()) {
/* Enables interrupts one instruction before HLT.
x86 special cases this so there is no race. */
safe_halt();
} else
local_irq_enable();
current_thread_info()->status |= TS_POLLING;
}
@ -129,16 +127,7 @@ static void default_idle(void)
*/
static void poll_idle (void)
{
local_irq_enable();
asm volatile(
"2:"
"testl %0,%1;"
"rep; nop;"
"je 2b;"
: :
"i" (_TIF_NEED_RESCHED),
"m" (current_thread_info()->flags));
cpu_relax();
}
void cpu_idle_wait(void)
@ -257,8 +246,7 @@ void mwait_idle_with_hints(unsigned long eax, unsigned long ecx)
static void mwait_idle(void)
{
local_irq_enable();
while (!need_resched())
mwait_idle_with_hints(0,0);
mwait_idle_with_hints(0,0);
}
void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c)