Dear ADEOS users,
2.6.25 seems to show abnormal latencies on hardware that showed good
performances up to 2.6.24. We think we traced down the issue to x86's
process_xx.c, which disappeared after regressing default_idle() to
2.6.24. The related changes are described in the attached patch.
Sincerely, p.
--- process_32.c.orig 2008-04-17 04:49:44.000000000 +0200
+++ process_32.c 2008-06-16 09:38:20.000000000 +0200
@@ -111,20 +111,25 @@ void default_idle(void)
*/
smp_mb();
- local_irq_disable();
+ local_irq_disable_hw();
if (!need_resched()) {
+#ifndef CONFIG_IPIPE
ktime_t t0, t1;
u64 t0n, t1n;
t0 = ktime_get();
t0n = ktime_to_ns(t0);
+#endif
safe_halt(); /* enables interrupts racelessly */
+#ifndef CONFIG_IPIPE
local_irq_disable();
t1 = ktime_get();
t1n = ktime_to_ns(t1);
sched_clock_idle_wakeup_event(t1n - t0n);
- }
- local_irq_enable();
+ local_irq_enable(); /* This will force enable_hw as well. */
+#endif
+ } else
+ local_irq_enable_hw();
current_thread_info()->status |= TS_POLLING;
} else {
/* loop is done by the caller */
@@ -203,6 +208,7 @@ void cpu_idle(void)
play_dead();
__get_cpu_var(irq_stat).idle_timestamp = jiffies;
+ ipipe_suspend_domain();
idle();
}
tick_nohz_restart_sched_tick();
@@ -269,6 +275,11 @@ static int __cpuinit mwait_usable(const
void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c)
{
+#ifdef CONFIG_IPIPE
+#define default_to_mwait force_mwait
+#else
+#define default_to_mwait 1
+#endif
static int selected;
if (selected)
@@ -284,7 +295,7 @@ void __cpuinit select_idle_routine(const
* Skip, if setup has overridden idle.
* One CPU supports mwait => All CPUs supports mwait
*/
- if (!pm_idle) {
+ if (!pm_idle && default_to_mwait) {
printk(KERN_INFO "using mwait in idle threads.\n");
pm_idle = mwait_idle;
}
--- process_64.c.orig 2008-04-17 04:49:44.000000000 +0200
+++ process_64.c 2008-06-16 09:38:20.000000000 +0200
@@ -53,6 +53,8 @@
asmlinkage extern void ret_from_fork(void);
+asmlinkage extern void thread_return(void);
+
unsigned long kernel_thread_flags = CLONE_VM | CLONE_UNTRACED;
unsigned long boot_option_idle_override = 0;
@@ -105,20 +107,25 @@ void default_idle(void)
* test NEED_RESCHED:
*/
smp_mb();
- local_irq_disable();
+ local_irq_disable_hw();
if (!need_resched()) {
+#ifndef CONFIG_IPIPE
ktime_t t0, t1;
u64 t0n, t1n;
t0 = ktime_get();
t0n = ktime_to_ns(t0);
+#endif
safe_halt(); /* enables interrupts racelessly */
+#ifndef CONFIG_IPIPE
local_irq_disable();
t1 = ktime_get();
t1n = ktime_to_ns(t1);
sched_clock_idle_wakeup_event(t1n - t0n);
- }
- local_irq_enable();
+ local_irq_enable(); /* This will force enable_hw as well. */
+#endif
+ } else
+ local_irq_enable_hw();
current_thread_info()->status |= TS_POLLING;
}
@@ -185,6 +192,7 @@ void cpu_idle(void)
*/
local_irq_disable();
enter_idle();
+ ipipe_suspend_domain();
idle();
/* In many cases the interrupt that ended idle
has already called exit_idle. But some idle
@@ -265,6 +273,11 @@ static int __cpuinit mwait_usable(const
void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c)
{
+#ifdef CONFIG_IPIPE
+#define default_to_mwait force_mwait
+#else
+#define default_to_mwait 1
+#endif
static int selected;
if (selected)
@@ -280,7 +293,7 @@ void __cpuinit select_idle_routine(const
* Skip, if setup has overridden idle.
* One CPU supports mwait => All CPUs supports mwait
*/
- if (!pm_idle) {
+ if (!pm_idle && default_to_mwait) {
printk(KERN_INFO "using mwait in idle threads.\n");
pm_idle = mwait_idle;
}
@@ -483,6 +496,7 @@ int copy_thread(int nr, unsigned long cl
p->thread.sp = (unsigned long) childregs;
p->thread.sp0 = (unsigned long) (childregs+1);
p->thread.usersp = me->thread.usersp;
+ p->thread.rip = (unsigned long) thread_return;
set_tsk_thread_flag(p, TIF_FORK);
@@ -602,7 +616,7 @@ __switch_to(struct task_struct *prev_p,
{
struct thread_struct *prev = &prev_p->thread,
*next = &next_p->thread;
- int cpu = smp_processor_id();
+ int cpu = raw_smp_processor_id();
struct tss_struct *tss = &per_cpu(init_tss, cpu);
/* we're going to use this soon, after a few expensive things */
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