There seems to be quite a bit of confusion and possible problems
in the cpu_idle code of many architectures. Hopefully many will
be false positives, but please bear with me and read this and check
your code if you maintain:
alpha, arm26, h8300, ia64, m68knommu, ia64, parisc, ppc64, s390,
sh64, sparc, um, or xtensa.
OK, so I've send a patch to Andrew that makes the various rules
a bit clearer (this did not introduce arch bugs, I found them when
making this patch). I've attached the complete patch at the end
of this email. You *ONLY* need to look at the small changes to your
architecture, and read the following rules.
Your cpu_idle routines need to obey the following rules:
****
1. Preempt should now disabled over idle routines. Should only be enabled
to call schedule() then disabled again.
2. need_resched/TIF_NEED_RESCHED is only ever set, and will never be
cleared until the running task has called schedule(). Idle threads only
ever need to query need_resched, never set or clear it.
3. When cpu_idle finds (need_resched() == 'true'), it should call schedule().
It should not call schedule() otherwise.
4. The only time interrupts need to be disabled when checking need_resched
is if we are about to sleep the processor until the next interrupt (this
doesn't provide any protection of need_resched, it prevents losing an
interrupt).
4a. Common problem with this type of sleep appears to be:
local_irq_disable();
if (!need_resched()) {
local_irq_enable();
*** resched interrupt arrives here ***
__asm__("sleep until next interrupt");
}
5. TIF_POLLING_NRFLAG can be set by idle routines that do not need an interrupt
to wake them up when need_resched goes high. If TIF_POLLING_NRFLAG is set,
and we do decide to enter an interrupt sleep, it needs to be cleared then a
memory barrier issued (followed by a test of need_resched with interrupts
disabled, as explained in 3).
****
Possible arch problems I found (and either tried to fix or didn't):
alpha - set TIF_POLLING_NRFLAG. OK?
arm26 - how did it work?! It didn't appear to ever call schedule() (See#4).
I don't know how it could have run other processes without
CONFIG_PREEMPT (fixed? please check!)
h8300 - Fixed(?) to "sleep" only if need_resched is NOT set. (See #3)
- Is such sleeping racy vs interrupts? (See #4a).
The H8/300 manual I found indicates yes, however disabling IRQs
over the sleep mean only NMIs can wake it up, so can't fix easily
without doing spin waiting.
ia64 - is safe_halt call racy vs interrupts? (See #4a)
m68knommu - Fixed(?) to "stop" only if need_resched() is NOT set. (See #3)
- Is such sleeping racy vs interrupts? (See #4a)
parisc - set TIF_POLLING_NRFLAG. OK?
ppc64 - dont test or clear need_resched in cpu_idle. (See #2)
s390 - local irq disable before checking need_resched doesn't gain
anything (removed, OK?)
sh64 - Is sleeping racy vs interrupts? (See #4a)
sparc - IRQs on at this point(?), change local_irq_save to _disable.
- Changed idle loop so don't go to schedule() if pm_idle is NULL!
- set TIF_POLLING_NRFLAG for SMP.
- TODO: needs secondary CPUs to disable preempt (See #1)
um - I'm too lazy to really look. Might be OK :P
xtensa - obviously not tested with preempt (hopefully fixed?)
And attached is the patch, for reference. Please make sure what fixes
I have made are correct, and what concerns I have raised are checked.
Feel free to ask for help or clarification of anything.
Thanks,
Nick
--
SUSE Labs, Novell Inc.
Make some changes to the NEED_RESCHED and POLLING_NRFLAG to reduce
confusion, and make their semantics rigid. Also have preempt explicitly
disabled in idle routines. Improves efficiency of resched_task and some
cpu_idle routines.
* In resched_task:
- TIF_NEED_RESCHED is only cleared with the task's runqueue lock held,
and as we hold it during resched_task, then there is no need for an
atomic test and set there. The only other time this should be set is
when the task's quantum expires, in the timer interrupt - this is
protected against because the rq lock is irq-safe.
- If TIF_NEED_RESCHED is set, then we don't need to do anything. It
won't get unset until the task get's schedule()d off.
- If we are running on the same CPU as the task we resched, then set
TIF_NEED_RESCHED and no further action is required.
- If we are running on another CPU, and TIF_POLLING_NRFLAG is *not* set
after TIF_NEED_RESCHED has been set, then we need to send an IPI.
Using these rules, we are able to remove the test and set operation in
resched_task, and make clear the previously vague semantics of POLLING_NRFLAG.
* In idle routines:
- Enter cpu_idle with preempt disabled. When the need_resched() condition
becomes true, explicitly call schedule(). This makes things a bit clearer
(IMO), but haven't updated all architectures yet.
- Many do a test and clear of TIF_NEED_RESCHED for some reason. According
to the resched_task rules, this isn't needed (and actually breaks the
assumption that TIF_NEED_RESCHED is only cleared with the runqueue lock
held). So remove that. Generally one less locked memory op when switching
to the idle thread.
- Many idle routines clear TIF_POLLING_NRFLAG, and only set it in the inner
most polling idle loops. The above resched_task semantics allow it to be
set until before the last time need_resched() is checked before going into
a halt requiring interrupt wakeup.
Many idle routines simply never enter such a halt, and so POLLING_NRFLAG
can be always left set, completely eliminating resched IPIs when rescheduling
the idle task.
POLLING_NRFLAG width can be increased, to reduce the chance of resched IPIs.
Index: linux-2.6/kernel/sched.c
===================================================================
--- linux-2.6.orig/kernel/sched.c 2005-05-29 14:21:21.000000000 +1000
+++ linux-2.6/kernel/sched.c 2005-05-29 14:21:42.000000000 +1000
@@ -845,21 +845,28 @@ static void deactivate_task(struct task_
#ifdef CONFIG_SMP
static void resched_task(task_t *p)
{
- int need_resched, nrpolling;
+ int cpu;
assert_spin_locked(&task_rq(p)->lock);
- /* minimise the chance of sending an interrupt to poll_idle() */
- nrpolling = test_tsk_thread_flag(p,TIF_POLLING_NRFLAG);
- need_resched = test_and_set_tsk_thread_flag(p,TIF_NEED_RESCHED);
- nrpolling |= test_tsk_thread_flag(p,TIF_POLLING_NRFLAG);
+ if (unlikely(test_tsk_thread_flag(p, TIF_NEED_RESCHED)))
+ return;
+
+ set_tsk_thread_flag(p, TIF_NEED_RESCHED);
- if (!need_resched && !nrpolling && (task_cpu(p) != smp_processor_id()))
- smp_send_reschedule(task_cpu(p));
+ cpu = task_cpu(p);
+ if (cpu == smp_processor_id())
+ return;
+
+ /* NEED_RESCHED must be visible before we test POLLING_NRFLAG */
+ smp_mb();
+ if (!test_tsk_thread_flag(p, TIF_POLLING_NRFLAG))
+ smp_send_reschedule(cpu);
}
#else
static inline void resched_task(task_t *p)
{
+ assert_spin_locked(&task_rq(p)->lock);
set_tsk_need_resched(p);
}
#endif
Index: linux-2.6/arch/i386/kernel/process.c
===================================================================
--- linux-2.6.orig/arch/i386/kernel/process.c 2005-05-29 14:21:21.000000000
+1000
+++ linux-2.6/arch/i386/kernel/process.c 2005-05-29 15:00:56.000000000
+1000
@@ -102,14 +102,22 @@ EXPORT_SYMBOL(enable_hlt);
*/
void default_idle(void)
{
+ local_irq_enable();
+
if (!hlt_counter && boot_cpu_data.hlt_works_ok) {
- local_irq_disable();
- if (!need_resched())
- safe_halt();
- else
- local_irq_enable();
+ clear_thread_flag(TIF_POLLING_NRFLAG);
+ smp_mb__after_clear_bit();
+ while (!need_resched()) {
+ local_irq_disable();
+ if (!need_resched())
+ safe_halt();
+ else
+ local_irq_enable();
+ }
+ set_thread_flag(TIF_POLLING_NRFLAG);
} else {
- cpu_relax();
+ while (!need_resched())
+ cpu_relax();
}
}
#ifdef CONFIG_APM_MODULE
@@ -123,29 +131,14 @@ EXPORT_SYMBOL(default_idle);
*/
static void poll_idle (void)
{
- int oldval;
-
local_irq_enable();
- /*
- * Deal with another CPU just having chosen a thread to
- * run here:
- */
- oldval = test_and_clear_thread_flag(TIF_NEED_RESCHED);
-
- if (!oldval) {
- set_thread_flag(TIF_POLLING_NRFLAG);
- asm volatile(
- "2:"
- "testl %0, %1;"
- "rep; nop;"
- "je 2b;"
- : : "i"(_TIF_NEED_RESCHED), "m"
(current_thread_info()->flags));
-
- clear_thread_flag(TIF_POLLING_NRFLAG);
- } else {
- set_need_resched();
- }
+ asm volatile(
+ "2:"
+ "testl %0, %1;"
+ "rep; nop;"
+ "je 2b;"
+ : : "i"(_TIF_NEED_RESCHED), "m" (current_thread_info()->flags));
}
#ifdef CONFIG_HOTPLUG_CPU
@@ -181,29 +174,32 @@ static inline void play_dead(void)
*/
void cpu_idle(void)
{
- int cpu = _smp_processor_id();
+ int cpu = smp_processor_id();
+ set_thread_flag(TIF_POLLING_NRFLAG);
+
/* endless idle loop with no priority at all */
while (1) {
- while (!need_resched()) {
- void (*idle)(void);
+ void (*idle)(void);
+
+ if (__get_cpu_var(cpu_idle_state))
+ __get_cpu_var(cpu_idle_state) = 0;
+
+ rmb();
+ idle = pm_idle;
+
+ if (!idle)
+ idle = default_idle;
+
+ if (cpu_is_offline(cpu))
+ play_dead();
- if (__get_cpu_var(cpu_idle_state))
- __get_cpu_var(cpu_idle_state) = 0;
+ __get_cpu_var(irq_stat).idle_timestamp = jiffies;
+ idle();
- rmb();
- idle = pm_idle;
-
- if (!idle)
- idle = default_idle;
-
- if (cpu_is_offline(cpu))
- play_dead();
-
- __get_cpu_var(irq_stat).idle_timestamp = jiffies;
- idle();
- }
+ preempt_enable_no_resched();
schedule();
+ preempt_disable();
}
}
@@ -246,15 +242,12 @@ static void mwait_idle(void)
{
local_irq_enable();
- if (!need_resched()) {
- set_thread_flag(TIF_POLLING_NRFLAG);
- do {
- __monitor((void *)¤t_thread_info()->flags, 0, 0);
- if (need_resched())
- break;
- __mwait(0, 0);
- } while (!need_resched());
- clear_thread_flag(TIF_POLLING_NRFLAG);
+ while (!need_resched()) {
+ __monitor((void *)¤t_thread_info()->flags, 0, 0);
+ smp_mb();
+ if (need_resched())
+ break;
+ __mwait(0, 0);
}
}
Index: linux-2.6/init/main.c
===================================================================
--- linux-2.6.orig/init/main.c 2005-05-29 14:21:21.000000000 +1000
+++ linux-2.6/init/main.c 2005-05-29 14:21:42.000000000 +1000
@@ -382,13 +382,14 @@ static void noinline rest_init(void)
kernel_thread(init, NULL, CLONE_FS | CLONE_SIGHAND);
numa_default_policy();
unlock_kernel();
- preempt_enable_no_resched();
/*
* The boot idle thread must execute schedule()
* at least once to get things moving:
*/
+ preempt_enable_no_resched();
schedule();
+ preempt_disable();
cpu_idle();
}
Index: linux-2.6/arch/i386/kernel/apm.c
===================================================================
--- linux-2.6.orig/arch/i386/kernel/apm.c 2005-05-29 14:21:21.000000000
+1000
+++ linux-2.6/arch/i386/kernel/apm.c 2005-05-29 14:21:42.000000000 +1000
@@ -767,8 +767,20 @@ static int set_system_power_state(u_shor
static int apm_do_idle(void)
{
u32 eax;
+ u8 ret;
+ int idled = 0;
- if (apm_bios_call_simple(APM_FUNC_IDLE, 0, 0, &eax)) {
+ clear_thread_flag(TIF_POLLING_NRFLAG);
+ smp_mb__after_clear_bit();
+ if (!need_resched()) {
+ idled = 1;
+ ret = apm_bios_call_simple(APM_FUNC_IDLE, 0, 0, &eax);
+ }
+ set_thread_flag(TIF_POLLING_NRFLAG);
+ if (!idled)
+ return 0;
+
+ if (ret) {
static unsigned long t;
/* This always fails on some SMP boards running UP kernels.
Index: linux-2.6/drivers/acpi/processor_idle.c
===================================================================
--- linux-2.6.orig/drivers/acpi/processor_idle.c 2005-05-29
14:21:21.000000000 +1000
+++ linux-2.6/drivers/acpi/processor_idle.c 2005-05-29 15:00:56.000000000
+1000
@@ -164,6 +164,14 @@ acpi_processor_power_activate (
return;
}
+static void acpi_safe_halt (void)
+{
+ clear_thread_flag(TIF_POLLING_NRFLAG);
+ smp_mb__after_clear_bit();
+ if (!need_resched())
+ safe_halt();
+ set_thread_flag(TIF_POLLING_NRFLAG);
+}
static atomic_t c3_cpu_count;
@@ -176,7 +184,7 @@ static void acpi_processor_idle (void)
int sleep_ticks = 0;
u32 t1, t2 = 0;
- pr = processors[_smp_processor_id()];
+ pr = processors[smp_processor_id()];
if (!pr)
return;
@@ -196,8 +204,13 @@ static void acpi_processor_idle (void)
}
cx = pr->power.state;
- if (!cx)
- goto easy_out;
+ if (!cx) {
+ if (pm_idle_save)
+ pm_idle_save();
+ else
+ acpi_safe_halt();
+ return;
+ }
/*
* Check BM Activity
@@ -277,7 +290,8 @@ static void acpi_processor_idle (void)
if (pm_idle_save)
pm_idle_save();
else
- safe_halt();
+ acpi_safe_halt();
+
/*
* TBD: Can't get time duration while in C1, as resumes
* go to an ISR rather than here. Need to instrument
@@ -407,16 +421,6 @@ end:
*/
if (next_state != pr->power.state)
acpi_processor_power_activate(pr, next_state);
-
- return;
-
- easy_out:
- /* do C1 instead of busy loop */
- if (pm_idle_save)
- pm_idle_save();
- else
- safe_halt();
- return;
}
Index: linux-2.6/arch/i386/kernel/smpboot.c
===================================================================
--- linux-2.6.orig/arch/i386/kernel/smpboot.c 2005-05-29 14:21:21.000000000
+1000
+++ linux-2.6/arch/i386/kernel/smpboot.c 2005-05-29 14:21:42.000000000
+1000
@@ -477,6 +477,8 @@ set_cpu_sibling_map(int cpu)
*/
static void __devinit start_secondary(void *unused)
{
+ preempt_disable();
+
/*
* Dont put anything before smp_callin(), SMP
* booting is too fragile that we want to limit the
Index: linux-2.6/arch/x86_64/kernel/process.c
===================================================================
--- linux-2.6.orig/arch/x86_64/kernel/process.c 2005-05-29 14:21:21.000000000
+1000
+++ linux-2.6/arch/x86_64/kernel/process.c 2005-05-29 15:00:56.000000000
+1000
@@ -85,12 +85,22 @@ EXPORT_SYMBOL(enable_hlt);
*/
void default_idle(void)
{
+ local_irq_enable();
+
if (!atomic_read(&hlt_counter)) {
- local_irq_disable();
- if (!need_resched())
- safe_halt();
- else
- local_irq_enable();
+ clear_thread_flag(TIF_POLLING_NRFLAG);
+ smp_mb__after_clear_bit();
+ while (!need_resched()) {
+ local_irq_disable();
+ if (!need_resched())
+ safe_halt();
+ else
+ local_irq_enable();
+ }
+ set_thread_flag(TIF_POLLING_NRFLAG);
+ } else {
+ while (!need_resched())
+ cpu_relax();
}
}
@@ -101,29 +111,16 @@ void default_idle(void)
*/
static void poll_idle (void)
{
- int oldval;
-
local_irq_enable();
- /*
- * Deal with another CPU just having chosen a thread to
- * run here:
- */
- oldval = test_and_clear_thread_flag(TIF_NEED_RESCHED);
-
- if (!oldval) {
- set_thread_flag(TIF_POLLING_NRFLAG);
- asm volatile(
- "2:"
- "testl %0,%1;"
- "rep; nop;"
- "je 2b;"
- : :
- "i" (_TIF_NEED_RESCHED),
- "m" (current_thread_info()->flags));
- } else {
- set_need_resched();
- }
+ asm volatile(
+ "2:"
+ "testl %0,%1;"
+ "rep; nop;"
+ "je 2b;"
+ : :
+ "i" (_TIF_NEED_RESCHED),
+ "m" (current_thread_info()->flags));
}
void cpu_idle_wait(void)
@@ -162,22 +159,25 @@ EXPORT_SYMBOL_GPL(cpu_idle_wait);
*/
void cpu_idle (void)
{
+ set_thread_flag(TIF_POLLING_NRFLAG);
+
/* endless idle loop with no priority at all */
while (1) {
- while (!need_resched()) {
- void (*idle)(void);
+ void (*idle)(void);
- if (__get_cpu_var(cpu_idle_state))
- __get_cpu_var(cpu_idle_state) = 0;
+ if (__get_cpu_var(cpu_idle_state))
+ __get_cpu_var(cpu_idle_state) = 0;
- rmb();
- idle = pm_idle;
- if (!idle)
- idle = default_idle;
- idle();
- }
+ rmb();
+ idle = pm_idle;
+ if (!idle)
+ idle = default_idle;
+
+ idle();
+ preempt_enable_no_resched();
schedule();
+ preempt_disable();
}
}
@@ -192,15 +192,12 @@ static void mwait_idle(void)
{
local_irq_enable();
- if (!need_resched()) {
- set_thread_flag(TIF_POLLING_NRFLAG);
- do {
- __monitor((void *)¤t_thread_info()->flags, 0, 0);
- if (need_resched())
- break;
- __mwait(0, 0);
- } while (!need_resched());
- clear_thread_flag(TIF_POLLING_NRFLAG);
+ while (!need_resched()) {
+ __monitor((void *)¤t_thread_info()->flags, 0, 0);
+ smp_mb();
+ if (need_resched())
+ break;
+ __mwait(0, 0);
}
}
Index: linux-2.6/arch/ppc64/kernel/idle.c
===================================================================
--- linux-2.6.orig/arch/ppc64/kernel/idle.c 2005-05-29 14:21:21.000000000
+1000
+++ linux-2.6/arch/ppc64/kernel/idle.c 2005-05-29 14:21:42.000000000 +1000
@@ -74,9 +74,10 @@ static void yield_shared_processor(void)
static int iSeries_idle(void)
{
struct paca_struct *lpaca;
- long oldval;
unsigned long CTRL;
+ set_thread_flag(TIF_POLLING_NRFLAG);
+
/* ensure iSeries run light will be out when idle */
clear_thread_flag(TIF_RUN_LIGHT);
CTRL = mfspr(CTRLF);
@@ -86,32 +87,21 @@ static int iSeries_idle(void)
lpaca = get_paca();
while (1) {
- if (lpaca->lppaca.shared_proc) {
- if (ItLpQueue_isLpIntPending(lpaca->lpqueue_ptr))
- process_iSeries_events();
- if (!need_resched())
- yield_shared_processor();
- } else {
- oldval = test_and_clear_thread_flag(TIF_NEED_RESCHED);
-
- if (!oldval) {
- set_thread_flag(TIF_POLLING_NRFLAG);
-
- while (!need_resched()) {
- HMT_medium();
- if
(ItLpQueue_isLpIntPending(lpaca->lpqueue_ptr))
- process_iSeries_events();
- HMT_low();
- }
-
+ while (!need_resched()) {
+ HMT_low();
+ if (ItLpQueue_isLpIntPending(lpaca->lpqueue_ptr)) {
HMT_medium();
- clear_thread_flag(TIF_POLLING_NRFLAG);
- } else {
- set_need_resched();
+ process_iSeries_events();
+ HMT_low();
}
+ if (lpaca->lppaca.shared_proc)
+ yield_shared_processor();
}
+ HMT_medium();
+ preempt_enable_no_resched();
schedule();
+ preempt_disable();
}
return 0;
@@ -121,32 +111,24 @@ static int iSeries_idle(void)
static int default_idle(void)
{
- long oldval;
unsigned int cpu = smp_processor_id();
-
+ set_thread_flag(TIF_POLLING_NRFLAG);
+
while (1) {
- oldval = test_and_clear_thread_flag(TIF_NEED_RESCHED);
-
- if (!oldval) {
- set_thread_flag(TIF_POLLING_NRFLAG);
-
- while (!need_resched() && !cpu_is_offline(cpu)) {
- barrier();
- /*
- * Go into low thread priority and possibly
- * low power mode.
- */
- HMT_low();
- HMT_very_low();
- }
-
- HMT_medium();
- clear_thread_flag(TIF_POLLING_NRFLAG);
- } else {
- set_need_resched();
+ while (!need_resched() && !cpu_is_offline(cpu)) {
+ barrier();
+ /*
+ * Go into low thread priority and possibly
+ * low power mode.
+ */
+ HMT_low();
+ HMT_very_low();
}
+ HMT_medium();
+ preempt_enable_no_resched();
schedule();
+ preempt_disable();
if (cpu_is_offline(cpu) && system_state == SYSTEM_RUNNING)
cpu_die();
}
@@ -160,12 +142,12 @@ DECLARE_PER_CPU(unsigned long, smt_snooz
int dedicated_idle(void)
{
- long oldval;
struct paca_struct *lpaca = get_paca(), *ppaca;
unsigned long start_snooze;
unsigned long *smt_snooze_delay = &__get_cpu_var(smt_snooze_delay);
unsigned int cpu = smp_processor_id();
+ set_thread_flag(TIF_POLLING_NRFLAG);
ppaca = &paca[cpu ^ 1];
while (1) {
@@ -175,66 +157,67 @@ int dedicated_idle(void)
*/
lpaca->lppaca.idle = 1;
- oldval = test_and_clear_thread_flag(TIF_NEED_RESCHED);
- if (!oldval) {
- set_thread_flag(TIF_POLLING_NRFLAG);
- start_snooze = __get_tb() +
+ start_snooze = __get_tb() +
*smt_snooze_delay * tb_ticks_per_usec;
- while (!need_resched() && !cpu_is_offline(cpu)) {
- /*
- * Go into low thread priority and possibly
- * low power mode.
- */
- HMT_low();
- HMT_very_low();
- if (*smt_snooze_delay == 0 ||
- __get_tb() < start_snooze)
- continue;
+ while (!need_resched() && !cpu_is_offline(cpu)) {
+ /*
+ * Go into low thread priority and possibly
+ * low power mode.
+ */
+ HMT_low();
+ HMT_very_low();
- HMT_medium();
+ if (*smt_snooze_delay == 0 || __get_tb() < start_snooze)
+ continue;
- if (!(ppaca->lppaca.idle)) {
- local_irq_disable();
+ HMT_medium();
- /*
- * We are about to sleep the thread
- * and so wont be polling any
- * more.
- */
- clear_thread_flag(TIF_POLLING_NRFLAG);
-
- /*
- * SMT dynamic mode. Cede will result
- * in this thread going dormant, if the
- * partner thread is still doing work.
- * Thread wakes up if partner goes idle,
- * an interrupt is presented, or a prod
- * occurs. Returning from the cede
- * enables external interrupts.
- */
- if (!need_resched())
- cede_processor();
- else
- local_irq_enable();
- } else {
- /*
- * Give the HV an opportunity at the
- * processor, since we are not doing
- * any work.
- */
- poll_pending();
- }
- }
+ if (!(ppaca->lppaca.idle)) {
+ local_irq_disable();
- clear_thread_flag(TIF_POLLING_NRFLAG);
- } else {
- set_need_resched();
+ /*
+ * We are about to sleep the thread
+ * and so wont be polling any
+ * more.
+ */
+ clear_thread_flag(TIF_POLLING_NRFLAG);
+
+ /*
+ * Must have TIF_POLLING_NRFLAG clear visible
+ * before checking need_resched
+ */
+ smp_mb__after_clear_bit();
+
+ /*
+ * SMT dynamic mode. Cede will result
+ * in this thread going dormant, if the
+ * partner thread is still doing work.
+ * Thread wakes up if partner goes idle,
+ * an interrupt is presented, or a prod
+ * occurs. Returning from the cede
+ * enables external interrupts.
+ */
+ if (!need_resched())
+ cede_processor();
+ else
+ local_irq_enable();
+ set_thread_flag(TIF_POLLING_NRFLAG);
+ } else {
+ /*
+ * Give the HV an opportunity at the
+ * processor, since we are not doing
+ * any work.
+ */
+ poll_pending();
+ }
}
HMT_medium();
lpaca->lppaca.idle = 0;
+ preempt_enable_no_resched();
schedule();
+ preempt_disable();
if (cpu_is_offline(cpu) && system_state == SYSTEM_RUNNING)
cpu_die();
}
@@ -245,6 +228,7 @@ static int shared_idle(void)
{
struct paca_struct *lpaca = get_paca();
unsigned int cpu = smp_processor_id();
+ set_thread_flag(TIF_POLLING_NRFLAG);
while (1) {
/*
@@ -256,6 +240,9 @@ static int shared_idle(void)
while (!need_resched() && !cpu_is_offline(cpu)) {
local_irq_disable();
+ clear_thread_flag(TIF_POLLING_NRFLAG);
+ smp_mb__after_clear_bit();
+
/*
* Yield the processor to the hypervisor. We return if
* an external interrupt occurs (which are driven prior
@@ -270,11 +257,14 @@ static int shared_idle(void)
cede_processor();
else
local_irq_enable();
+ set_thread_flag(TIF_POLLING_NRFLAG);
}
HMT_medium();
lpaca->lppaca.idle = 0;
+ preempt_enable_no_resched();
schedule();
+ preempt_disable();
if (cpu_is_offline(smp_processor_id()) &&
system_state == SYSTEM_RUNNING)
cpu_die();
@@ -289,10 +279,12 @@ static int native_idle(void)
{
while(1) {
/* check CPU type here */
- if (!need_resched())
+ while (!need_resched())
power4_idle();
- if (need_resched())
- schedule();
+
+ preempt_enable_no_resched();
+ schedule();
+ preempt_disable();
if (cpu_is_offline(_smp_processor_id()) &&
system_state == SYSTEM_RUNNING)
Index: linux-2.6/arch/ia64/kernel/process.c
===================================================================
--- linux-2.6.orig/arch/ia64/kernel/process.c 2005-05-29 14:21:21.000000000
+1000
+++ linux-2.6/arch/ia64/kernel/process.c 2005-05-29 14:21:42.000000000
+1000
@@ -195,11 +195,16 @@ update_pal_halt_status(int status)
void
default_idle (void)
{
- while (!need_resched())
- if (can_do_pal_halt)
+ if (can_do_pal_halt) {
+ clear_thread_flag(TIF_POLLING_NRFLAG);
+ smp_mb__after_clear_bit();
+ while (!need_resched())
safe_halt();
- else
+ set_thread_flag(TIF_POLLING_NRFLAG);
+ } else {
+ while (!need_resched())
cpu_relax();
+ }
}
#ifdef CONFIG_HOTPLUG_CPU
@@ -261,16 +266,16 @@ void __attribute__((noreturn))
cpu_idle (void)
{
void (*mark_idle)(int) = ia64_mark_idle;
+ int cpu = smp_processor_id();
+ set_thread_flag(TIF_POLLING_NRFLAG);
/* endless idle loop with no priority at all */
while (1) {
+ if (!need_resched()) {
+ void (*idle)(void);
#ifdef CONFIG_SMP
- if (!need_resched())
min_xtp();
#endif
- while (!need_resched()) {
- void (*idle)(void);
-
if (__get_cpu_var(cpu_idle_state))
__get_cpu_var(cpu_idle_state) = 0;
@@ -282,17 +287,17 @@ cpu_idle (void)
if (!idle)
idle = default_idle;
(*idle)();
- }
-
- if (mark_idle)
- (*mark_idle)(0);
-
+ if (mark_idle)
+ (*mark_idle)(0);
#ifdef CONFIG_SMP
- normal_xtp();
+ normal_xtp();
#endif
+ }
+ preempt_enable_no_resched();
schedule();
+ preempt_disable();
check_pgt_cache();
- if (cpu_is_offline(smp_processor_id()))
+ if (cpu_is_offline(cpu))
play_dead();
}
}
Index: linux-2.6/arch/ia64/kernel/smpboot.c
===================================================================
--- linux-2.6.orig/arch/ia64/kernel/smpboot.c 2005-05-29 14:21:21.000000000
+1000
+++ linux-2.6/arch/ia64/kernel/smpboot.c 2005-05-29 14:21:42.000000000
+1000
@@ -393,6 +393,8 @@ smp_callin (void)
int __devinit
start_secondary (void *unused)
{
+ preempt_disable();
+
/* Early console may use I/O ports */
ia64_set_kr(IA64_KR_IO_BASE, __pa(ia64_iobase));
Dprintk("start_secondary: starting CPU 0x%x\n",
hard_smp_processor_id());
Index: linux-2.6/arch/ppc64/kernel/smp.c
===================================================================
--- linux-2.6.orig/arch/ppc64/kernel/smp.c 2005-05-29 14:21:21.000000000
+1000
+++ linux-2.6/arch/ppc64/kernel/smp.c 2005-05-29 14:21:42.000000000 +1000
@@ -561,7 +561,10 @@ int __devinit __cpu_up(unsigned int cpu)
/* Activate a secondary processor. */
int __devinit start_secondary(void *unused)
{
- unsigned int cpu = smp_processor_id();
+ unsigned int cpu;
+
+ preempt_disable();
+ cpu = smp_processor_id();
atomic_inc(&init_mm.mm_count);
current->active_mm = &init_mm;
Index: linux-2.6/arch/sparc64/kernel/smp.c
===================================================================
--- linux-2.6.orig/arch/sparc64/kernel/smp.c 2005-05-29 14:21:21.000000000
+1000
+++ linux-2.6/arch/sparc64/kernel/smp.c 2005-05-29 14:21:42.000000000 +1000
@@ -144,6 +144,9 @@ void __init smp_callin(void)
membar("#LoadLoad");
cpu_set(cpuid, cpu_online_map);
+
+ /* idle thread is expected to have preempt disabled */
+ preempt_disable();
}
void cpu_panic(void)
@@ -1167,20 +1170,9 @@ void __init smp_cpus_done(unsigned int m
(bogosum/(5000/HZ))%100);
}
-/* This needn't do anything as we do not sleep the cpu
- * inside of the idler task, so an interrupt is not needed
- * to get a clean fast response.
- *
- * XXX Reverify this assumption... -DaveM
- *
- * Addendum: We do want it to do something for the signal
- * delivery case, we detect that by just seeing
- * if we are trying to send this to an idler or not.
- */
void smp_send_reschedule(int cpu)
{
- if (cpu_data(cpu).idle_volume == 0)
- smp_receive_signal(cpu);
+ smp_receive_signal(cpu);
}
/* This is a nop because we capture all other cpus
Index: linux-2.6/arch/sparc64/kernel/process.c
===================================================================
--- linux-2.6.orig/arch/sparc64/kernel/process.c 2005-05-29
14:21:21.000000000 +1000
+++ linux-2.6/arch/sparc64/kernel/process.c 2005-05-29 14:21:42.000000000
+1000
@@ -74,7 +74,9 @@ void cpu_idle(void)
while (!need_resched())
barrier();
+ preempt_enable_no_resched();
schedule();
+ preempt_disable();
check_pgt_cache();
}
}
@@ -83,21 +85,31 @@ void cpu_idle(void)
/*
* the idle loop on a UltraMultiPenguin...
+ *
+ * TIF_POLLING_NRFLAG is set because we do not sleep the cpu
+ * inside of the idler task, so an interrupt is not needed
+ * to get a clean fast response.
+ *
+ * XXX Reverify this assumption... -DaveM
+ *
+ * Addendum: We do want it to do something for the signal
+ * delivery case, we detect that by just seeing
+ * if we are trying to send this to an idler or not.
*/
-#define idle_me_harder() (cpu_data(smp_processor_id()).idle_volume += 1)
-#define unidle_me() (cpu_data(smp_processor_id()).idle_volume = 0)
void cpu_idle(void)
{
+ cpuinfo_sparc *cpuinfo = &local_cpu_data();
set_thread_flag(TIF_POLLING_NRFLAG);
+
while(1) {
if (need_resched()) {
- unidle_me();
- clear_thread_flag(TIF_POLLING_NRFLAG);
+ cpuinfo->idle_volume = 0;
+ preempt_enable_no_resched();
schedule();
- set_thread_flag(TIF_POLLING_NRFLAG);
+ preempt_disable();
check_pgt_cache();
}
- idle_me_harder();
+ cpuinfo->idle_volume++;
/* The store ordering is so that IRQ handlers on
* other cpus see our increasing idleness for the buddy
Index: linux-2.6/arch/alpha/kernel/process.c
===================================================================
--- linux-2.6.orig/arch/alpha/kernel/process.c 2005-05-29 14:21:21.000000000
+1000
+++ linux-2.6/arch/alpha/kernel/process.c 2005-05-29 14:21:42.000000000
+1000
@@ -43,22 +43,20 @@
#include "proto.h"
#include "pci_impl.h"
-void default_idle(void)
-{
- barrier();
-}
-
void
cpu_idle(void)
{
+ set_thread_flag(TIF_POLLING_NRFLAG);
+
while (1) {
- void (*idle)(void) = default_idle;
/* FIXME -- EV6 and LCA45 know how to power down
the CPU. */
while (!need_resched())
- idle();
+ cpu_relax();
+ preempt_enable_no_resched();
schedule();
+ preempt_disable();
}
}
Index: linux-2.6/arch/alpha/kernel/smp.c
===================================================================
--- linux-2.6.orig/arch/alpha/kernel/smp.c 2005-05-29 14:21:21.000000000
+1000
+++ linux-2.6/arch/alpha/kernel/smp.c 2005-05-29 14:21:42.000000000 +1000
@@ -128,7 +128,11 @@ wait_boot_cpu_to_stop(int cpuid)
void __init
smp_callin(void)
{
- int cpuid = hard_smp_processor_id();
+ int cpuid;
+
+ preempt_disable();
+
+ cpuid = hard_smp_processor_id();
if (cpu_test_and_set(cpuid, cpu_online_map)) {
printk("??, cpu 0x%x already present??\n", cpuid);
Index: linux-2.6/arch/s390/kernel/smp.c
===================================================================
--- linux-2.6.orig/arch/s390/kernel/smp.c 2005-05-29 14:21:21.000000000
+1000
+++ linux-2.6/arch/s390/kernel/smp.c 2005-05-29 14:21:42.000000000 +1000
@@ -528,6 +528,8 @@ extern void pfault_fini(void);
int __devinit start_secondary(void *cpuvoid)
{
+ preempt_disable();
+
/* Setup the cpu */
cpu_init();
/* init per CPU timer */
Index: linux-2.6/arch/sparc/kernel/process.c
===================================================================
--- linux-2.6.orig/arch/sparc/kernel/process.c 2005-05-29 14:21:21.000000000
+1000
+++ linux-2.6/arch/sparc/kernel/process.c 2005-05-29 14:21:42.000000000
+1000
@@ -72,6 +72,13 @@ struct thread_info *current_set[NR_CPUS]
*/
void default_idle(void)
{
+ if (pm_idle) {
+ while (!need_resched())
+ (*pm_idle)();
+ } else {
+ while (!need_resched())
+ cpu_relax();
+ }
}
#ifndef CONFIG_SMP
@@ -92,12 +99,11 @@ void cpu_idle(void)
static unsigned long fps;
unsigned long now;
unsigned long faults;
- unsigned long flags;
extern unsigned long sun4c_kernel_faults;
extern void sun4c_grow_kernel_ring(void);
- local_irq_save(flags);
+ local_irq_disable();
now = jiffies;
count -= (now - last_jiffies);
last_jiffies = now;
@@ -113,14 +119,14 @@ void cpu_idle(void)
sun4c_grow_kernel_ring();
}
}
- local_irq_restore(flags);
+ local_irq_enable();
}
- while((!need_resched()) && pm_idle) {
- (*pm_idle)();
- }
+ default_idle();
+ preempt_enable_no_resched();
schedule();
+ preempt_disable();
check_pgt_cache();
}
}
@@ -130,13 +136,17 @@ void cpu_idle(void)
/* This is being executed in task 0 'user space'. */
void cpu_idle(void)
{
+ set_thread_flag(TIF_POLLING_NRFLAG);
+
/* endless idle loop with no priority at all */
while(1) {
- if(need_resched()) {
- schedule();
- check_pgt_cache();
- }
- barrier(); /* or else gcc optimizes... */
+ while (!need_resched())
+ cpu_relax();
+
+ preempt_enable_no_resched();
+ schedule();
+ preempt_disable();
+ check_pgt_cache();
}
}
Index: linux-2.6/arch/ppc/kernel/idle.c
===================================================================
--- linux-2.6.orig/arch/ppc/kernel/idle.c 2005-05-29 14:21:21.000000000
+1000
+++ linux-2.6/arch/ppc/kernel/idle.c 2005-05-29 14:21:42.000000000 +1000
@@ -50,8 +50,6 @@ void default_idle(void)
}
#endif
}
- if (need_resched())
- schedule();
}
/*
@@ -59,11 +57,18 @@ void default_idle(void)
*/
void cpu_idle(void)
{
- for (;;)
- if (ppc_md.idle != NULL)
- ppc_md.idle();
- else
- default_idle();
+ for (;;) {
+ while (need_resched()) {
+ if (ppc_md.idle != NULL)
+ ppc_md.idle();
+ else
+ default_idle();
+ }
+
+ preempt_enable_no_resched();
+ schedule();
+ preempt_disable();
+ }
}
#if defined(CONFIG_SYSCTL) && defined(CONFIG_6xx)
Index: linux-2.6/arch/m32r/kernel/process.c
===================================================================
--- linux-2.6.orig/arch/m32r/kernel/process.c 2005-05-29 14:21:21.000000000
+1000
+++ linux-2.6/arch/m32r/kernel/process.c 2005-05-29 14:21:42.000000000
+1000
@@ -104,7 +104,9 @@ void cpu_idle (void)
idle();
}
+ preempt_enable_no_resched();
schedule();
+ preempt_disable();
}
}
Index: linux-2.6/arch/frv/kernel/process.c
===================================================================
--- linux-2.6.orig/arch/frv/kernel/process.c 2005-05-29 14:21:21.000000000
+1000
+++ linux-2.6/arch/frv/kernel/process.c 2005-05-29 14:21:42.000000000 +1000
@@ -77,16 +77,20 @@ void (*idle)(void) = core_sleep_idle;
*/
void cpu_idle(void)
{
+ int cpu = smp_processor_id();
+
/* endless idle loop with no priority at all */
while (1) {
while (!need_resched()) {
- irq_stat[smp_processor_id()].idle_timestamp = jiffies;
+ irq_stat[cpu].idle_timestamp = jiffies;
if (!frv_dma_inprogress && idle)
idle();
}
-
+
+ preempt_enable_no_resched();
schedule();
+ preempt_disable();
}
}
Index: linux-2.6/arch/cris/kernel/process.c
===================================================================
--- linux-2.6.orig/arch/cris/kernel/process.c 2005-05-29 14:21:21.000000000
+1000
+++ linux-2.6/arch/cris/kernel/process.c 2005-05-29 14:21:42.000000000
+1000
@@ -201,7 +201,9 @@ void cpu_idle (void)
idle();
}
+ preempt_enable_no_resched();
schedule();
+ preempt_disable();
}
}
Index: linux-2.6/arch/mips/kernel/smp.c
===================================================================
--- linux-2.6.orig/arch/mips/kernel/smp.c 2005-05-29 14:21:21.000000000
+1000
+++ linux-2.6/arch/mips/kernel/smp.c 2005-05-29 14:21:42.000000000 +1000
@@ -83,7 +83,11 @@ extern ATTRIB_NORET void cpu_idle(void);
*/
asmlinkage void start_secondary(void)
{
- unsigned int cpu = smp_processor_id();
+ unsigned int cpu;
+
+ preempt_disable();
+
+ cpu = smp_processor_id();
cpu_probe();
cpu_report();
Index: linux-2.6/arch/parisc/kernel/process.c
===================================================================
--- linux-2.6.orig/arch/parisc/kernel/process.c 2005-05-29 14:21:21.000000000
+1000
+++ linux-2.6/arch/parisc/kernel/process.c 2005-05-29 14:21:42.000000000
+1000
@@ -88,11 +88,15 @@ void default_idle(void)
*/
void cpu_idle(void)
{
+ set_thread_flag(TIF_POLLING_NRFLAG);
+
/* endless idle loop with no priority at all */
while (1) {
while (!need_resched())
barrier();
+ preempt_enable_no_resched();
schedule();
+ preempt_disable();
check_pgt_cache();
}
}
Index: linux-2.6/arch/ppc/kernel/smp.c
===================================================================
--- linux-2.6.orig/arch/ppc/kernel/smp.c 2005-05-29 14:21:21.000000000
+1000
+++ linux-2.6/arch/ppc/kernel/smp.c 2005-05-29 14:21:42.000000000 +1000
@@ -326,6 +326,8 @@ int __devinit start_secondary(void *unus
{
int cpu;
+ preempt_disable();
+
atomic_inc(&init_mm.mm_count);
current->active_mm = &init_mm;
Index: linux-2.6/arch/sh/kernel/process.c
===================================================================
--- linux-2.6.orig/arch/sh/kernel/process.c 2005-05-29 14:21:21.000000000
+1000
+++ linux-2.6/arch/sh/kernel/process.c 2005-05-29 14:21:42.000000000 +1000
@@ -51,28 +51,24 @@ void enable_hlt(void)
EXPORT_SYMBOL(enable_hlt);
-void default_idle(void)
+void cpu_idle(void)
{
/* endless idle loop with no priority at all */
while (1) {
if (hlt_counter) {
- while (1)
- if (need_resched())
- break;
+ while (!need_resched())
+ cpu_relax();
} else {
while (!need_resched())
cpu_sleep();
}
+ preempt_disable_no_resched();
schedule();
+ preempt_enable();
}
}
-void cpu_idle(void)
-{
- default_idle();
-}
-
void machine_restart(char * __unused)
{
/* SR.BL=1 and invoke address error to let CPU reset (manual reset) */
Index: linux-2.6/arch/m68k/kernel/process.c
===================================================================
--- linux-2.6.orig/arch/m68k/kernel/process.c 2005-05-29 14:21:21.000000000
+1000
+++ linux-2.6/arch/m68k/kernel/process.c 2005-05-29 14:21:42.000000000
+1000
@@ -102,7 +102,9 @@ void cpu_idle(void)
while (1) {
while (!need_resched())
idle();
+ preempt_enable_no_resched();
schedule();
+ preempt_disable();
}
}
Index: linux-2.6/arch/mips/kernel/process.c
===================================================================
--- linux-2.6.orig/arch/mips/kernel/process.c 2005-05-29 14:21:21.000000000
+1000
+++ linux-2.6/arch/mips/kernel/process.c 2005-05-29 14:21:42.000000000
+1000
@@ -58,7 +58,9 @@ ATTRIB_NORET void cpu_idle(void)
while (!need_resched())
if (cpu_wait)
(*cpu_wait)();
+ preempt_enable_no_resched();
schedule();
+ preempt_disable()
}
}
Index: linux-2.6/arch/m68knommu/kernel/process.c
===================================================================
--- linux-2.6.orig/arch/m68knommu/kernel/process.c 2005-05-29
14:21:21.000000000 +1000
+++ linux-2.6/arch/m68knommu/kernel/process.c 2005-05-29 14:21:42.000000000
+1000
@@ -45,11 +45,8 @@ asmlinkage void ret_from_fork(void);
*/
void default_idle(void)
{
- while(1) {
- if (need_resched())
- __asm__("stop #0x2000" : : : "cc");
- schedule();
- }
+ while (!need_resched())
+ __asm__("stop #0x2000" : : : "cc");
}
void (*idle)(void) = default_idle;
@@ -63,7 +60,12 @@ void (*idle)(void) = default_idle;
void cpu_idle(void)
{
/* endless idle loop with no priority at all */
- idle();
+ while (1) {
+ idle();
+ preempt_enable_no_resched();
+ schedule();
+ preempt_disable();
+ }
}
void machine_restart(char * __unused)
Index: linux-2.6/arch/sh/kernel/smp.c
===================================================================
--- linux-2.6.orig/arch/sh/kernel/smp.c 2005-05-29 14:21:21.000000000 +1000
+++ linux-2.6/arch/sh/kernel/smp.c 2005-05-29 14:21:42.000000000 +1000
@@ -109,7 +109,11 @@ int __cpu_up(unsigned int cpu)
int start_secondary(void *unused)
{
- unsigned int cpu = smp_processor_id();
+ unsigned int cpu;
+
+ preempt_disable();
+
+ cpu = smp_processor_id();
atomic_inc(&init_mm.mm_count);
current->active_mm = &init_mm;
Index: linux-2.6/arch/parisc/kernel/smp.c
===================================================================
--- linux-2.6.orig/arch/parisc/kernel/smp.c 2005-05-29 14:21:21.000000000
+1000
+++ linux-2.6/arch/parisc/kernel/smp.c 2005-05-29 14:21:42.000000000 +1000
@@ -462,6 +462,8 @@ void __init smp_callin(void)
void *istack;
#endif
+ preempt_disable();
+
smp_cpu_init(slave_id);
#if 0 /* NOT WORKING YET - see entry.S */
Index: linux-2.6/arch/m32r/kernel/smpboot.c
===================================================================
--- linux-2.6.orig/arch/m32r/kernel/smpboot.c 2005-05-29 14:21:21.000000000
+1000
+++ linux-2.6/arch/m32r/kernel/smpboot.c 2005-05-29 14:21:42.000000000
+1000
@@ -424,6 +424,7 @@ void __init smp_cpus_done(unsigned int m
*==========================================================================*/
int __init start_secondary(void *unused)
{
+ preempt_disable();
cpu_init();
smp_callin();
while (!cpu_isset(smp_processor_id(), smp_commenced_mask))
Index: linux-2.6/arch/s390/kernel/process.c
===================================================================
--- linux-2.6.orig/arch/s390/kernel/process.c 2005-05-29 14:21:21.000000000
+1000
+++ linux-2.6/arch/s390/kernel/process.c 2005-05-29 14:21:42.000000000
+1000
@@ -101,11 +101,6 @@ void default_idle(void)
int cpu, rc;
local_irq_disable();
- if (need_resched()) {
- local_irq_enable();
- schedule();
- return;
- }
/* CPU is going idle. */
cpu = smp_processor_id();
@@ -121,7 +116,7 @@ void default_idle(void)
__ctl_set_bit(8, 15);
#ifdef CONFIG_HOTPLUG_CPU
- if (cpu_is_offline(smp_processor_id()))
+ if (cpu_is_offline(cpu))
cpu_die();
#endif
@@ -161,8 +156,13 @@ void default_idle(void)
void cpu_idle(void)
{
- for (;;)
- default_idle();
+ for (;;) {
+ while (!need_resched())
+ default_idle();
+ preempt_enable_no_resched();
+ schedule();
+ preempt_disable();
+ }
}
void show_regs(struct pt_regs *regs)
Index: linux-2.6/arch/sh64/kernel/process.c
===================================================================
--- linux-2.6.orig/arch/sh64/kernel/process.c 2005-05-29 14:21:21.000000000
+1000
+++ linux-2.6/arch/sh64/kernel/process.c 2005-05-29 14:21:42.000000000
+1000
@@ -307,23 +307,19 @@ __setup("hlt", hlt_setup);
static inline void hlt(void)
{
- if (hlt_counter)
- return;
-
__asm__ __volatile__ ("sleep" : : : "memory");
}
/*
* The idle loop on a uniprocessor SH..
*/
-void default_idle(void)
+void cpu_idle(void)
{
/* endless idle loop with no priority at all */
while (1) {
if (hlt_counter) {
- while (1)
- if (need_resched())
- break;
+ while (!need_resched())
+ cpu_relax();
} else {
local_irq_disable();
while (!need_resched()) {
@@ -334,13 +330,11 @@ void default_idle(void)
}
local_irq_enable();
}
+ preempt_enable_no_resched();
schedule();
+ preempt_disable();
}
-}
-void cpu_idle(void)
-{
- default_idle();
}
void machine_restart(char * __unused)
Index: linux-2.6/arch/arm26/kernel/process.c
===================================================================
--- linux-2.6.orig/arch/arm26/kernel/process.c 2005-05-29 14:21:21.000000000
+1000
+++ linux-2.6/arch/arm26/kernel/process.c 2005-05-29 14:21:42.000000000
+1000
@@ -74,15 +74,13 @@ __setup("hlt", hlt_setup);
void cpu_idle(void)
{
/* endless idle loop with no priority at all */
- preempt_disable();
while (1) {
- while (!need_resched()) {
- local_irq_disable();
- if (!need_resched() && !hlt_counter)
- local_irq_enable();
- }
+ while (!need_resched())
+ cpu_relax();
+ preempt_enable_no_resched();
+ schedule();
+ preempt_disable();
}
- schedule();
}
static char reboot_mode = 'h';
Index: linux-2.6/arch/arm/kernel/process.c
===================================================================
--- linux-2.6.orig/arch/arm/kernel/process.c 2005-05-29 14:21:21.000000000
+1000
+++ linux-2.6/arch/arm/kernel/process.c 2005-05-29 14:21:42.000000000 +1000
@@ -84,10 +84,14 @@ EXPORT_SYMBOL(pm_power_off);
*/
void default_idle(void)
{
- local_irq_disable();
- if (!need_resched() && !hlt_counter)
- arch_idle();
- local_irq_enable();
+ if (hlt_counter)
+ cpu_relax()
+ else {
+ local_irq_disable();
+ if (!need_resched())
+ arch_idle();
+ local_irq_enable();
+ }
}
/*
@@ -104,13 +108,13 @@ void cpu_idle(void)
void (*idle)(void) = pm_idle;
if (!idle)
idle = default_idle;
- preempt_disable();
leds_event(led_idle_start);
while (!need_resched())
idle();
leds_event(led_idle_end);
- preempt_enable();
+ preempt_enable_no_resched();
schedule();
+ preempt_disable();
}
}
Index: linux-2.6/arch/h8300/kernel/process.c
===================================================================
--- linux-2.6.orig/arch/h8300/kernel/process.c 2005-05-29 14:21:21.000000000
+1000
+++ linux-2.6/arch/h8300/kernel/process.c 2005-05-29 15:01:05.000000000
+1000
@@ -53,22 +53,17 @@ asmlinkage void ret_from_fork(void);
#if !defined(CONFIG_H8300H_SIM) && !defined(CONFIG_H8S_SIM)
void default_idle(void)
{
- while(1) {
- if (need_resched()) {
- local_irq_enable();
- __asm__("sleep");
- local_irq_disable();
- }
- schedule();
+ local_irq_disable();
+ if (!need_resched()) {
+ local_irq_enable();
+ /* XXX: race here! What if need_resched() gets set now? */
+ __asm__("sleep");
}
}
#else
void default_idle(void)
{
- while(1) {
- if (need_resched())
- schedule();
- }
+ cpu_relax();
}
#endif
void (*idle)(void) = default_idle;
@@ -81,7 +76,13 @@ void (*idle)(void) = default_idle;
*/
void cpu_idle(void)
{
- idle();
+ while (1) {
+ while (!need_resched())
+ idle();
+ preempt_enable_no_resched();
+ schedule();
+ preempt_disable();
+ }
}
void machine_restart(char * __unused)
Index: linux-2.6/arch/xtensa/kernel/process.c
===================================================================
--- linux-2.6.orig/arch/xtensa/kernel/process.c 2005-05-29 14:21:21.000000000
+1000
+++ linux-2.6/arch/xtensa/kernel/process.c 2005-05-29 14:21:42.000000000
+1000
@@ -96,8 +96,9 @@ void cpu_idle(void)
while (1) {
while (!need_resched())
platform_idle();
- preempt_enable();
+ preempt_enable_no_resched();
schedule();
+ preempt_disable();
}
}
Index: linux-2.6/arch/v850/kernel/process.c
===================================================================
--- linux-2.6.orig/arch/v850/kernel/process.c 2005-05-29 14:21:21.000000000
+1000
+++ linux-2.6/arch/v850/kernel/process.c 2005-05-29 14:21:42.000000000
+1000
@@ -36,11 +36,8 @@ extern void ret_from_fork (void);
/* The idle loop. */
void default_idle (void)
{
- while (1) {
- while (! need_resched ())
- asm ("halt; nop; nop; nop; nop; nop" ::: "cc");
- schedule ();
- }
+ while (! need_resched ())
+ asm ("halt; nop; nop; nop; nop; nop" ::: "cc");
}
void (*idle)(void) = default_idle;
@@ -54,7 +51,14 @@ void (*idle)(void) = default_idle;
void cpu_idle (void)
{
/* endless idle loop with no priority at all */
- (*idle) ();
+ while (1) {
+ while (!need_resched())
+ (*idle) ();
+
+ preempt_enable_no_resched();
+ schedule();
+ preempt_disable();
+ }
}
/*
