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authorAndi Kleen <ak@suse.de>2006-09-26 10:52:40 +0200
committerAndi Kleen <andi@basil.nowhere.org>2006-09-26 10:52:40 +0200
commita15da49debaf7f09460a886b0ecd08588410715e (patch)
tree685ed022695ff03cec167c6690815e08191a803c
parent[PATCH] Remove experimental mark of kexec (diff)
downloadlinux-a15da49debaf7f09460a886b0ecd08588410715e.tar.xz
linux-a15da49debaf7f09460a886b0ecd08588410715e.zip
[PATCH] Fix idle notifiers
Previously exit_idle would be called more often than enter_idle Now instead of using complicated tests just keep track of it using the per CPU variable as a flip flop. I moved the idle state into the PDA to make the access more efficient. Original bug report and an initial patch from Stephane Eranian, but redone by AK. Cc: Stephane Eranian <eranian@hpl.hp.com> Signed-off-by: Andi Kleen <ak@suse.de>
-rw-r--r--arch/x86_64/kernel/process.c15
-rw-r--r--include/asm-x86_64/pda.h3
2 files changed, 11 insertions, 7 deletions
diff --git a/arch/x86_64/kernel/process.c b/arch/x86_64/kernel/process.c
index 885c318f76ab..458006ae19f3 100644
--- a/arch/x86_64/kernel/process.c
+++ b/arch/x86_64/kernel/process.c
@@ -80,25 +80,25 @@ void idle_notifier_unregister(struct notifier_block *n)
}
EXPORT_SYMBOL(idle_notifier_unregister);
-enum idle_state { CPU_IDLE, CPU_NOT_IDLE };
-static DEFINE_PER_CPU(enum idle_state, idle_state) = CPU_NOT_IDLE;
-
void enter_idle(void)
{
- __get_cpu_var(idle_state) = CPU_IDLE;
+ write_pda(isidle, 1);
atomic_notifier_call_chain(&idle_notifier, IDLE_START, NULL);
}
static void __exit_idle(void)
{
- __get_cpu_var(idle_state) = CPU_NOT_IDLE;
+ if (read_pda(isidle) == 0)
+ return;
+ write_pda(isidle, 0);
atomic_notifier_call_chain(&idle_notifier, IDLE_END, NULL);
}
/* Called from interrupts to signify idle end */
void exit_idle(void)
{
- if (current->pid | read_pda(irqcount))
+ /* idle loop has pid 0 */
+ if (current->pid)
return;
__exit_idle();
}
@@ -220,6 +220,9 @@ void cpu_idle (void)
play_dead();
enter_idle();
idle();
+ /* 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();
}
diff --git a/include/asm-x86_64/pda.h b/include/asm-x86_64/pda.h
index 531f48a6c3af..14996d962bac 100644
--- a/include/asm-x86_64/pda.h
+++ b/include/asm-x86_64/pda.h
@@ -25,7 +25,8 @@ struct x8664_pda {
int nodenumber; /* number of current node */
unsigned int __softirq_pending;
unsigned int __nmi_count; /* number of NMI on this CPUs */
- int mmu_state;
+ short mmu_state;
+ short isidle;
struct mm_struct *active_mm;
unsigned apic_timer_irqs;
} ____cacheline_aligned_in_smp;