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Message-ID: <20060831144011.GA26187@frankl.hpl.hp.com>
Date: Thu, 31 Aug 2006 07:40:11 -0700
From: Stephane Eranian <eranian@....hp.com>
To: linux-kernel@...r.kernel.org
Cc: Stephane Eranian <eranian@....hp.com>
Subject: [PATCH] x86_64 fix idle notifier
Hello,
Here is a patch against Linus GIT tree that fixes the idle notifier
for the X86-64 tree. With this notifiier you can get called when
entering/exiting the core of the idle loop. I don't think it is used
yet but I am planning to leverage it for perfmon.
There was an issue in that it would not capture all re-entries into the
idle loop because of missing hooks on the return from interrupt path.
I have also modified the header file (idle.h) to avoid branching in
case this is not needed. The enter_idle()/exit_idle() calls are not
integrated into irq_enter()/irq_exit() because those are generic and
for now the idle notifier is arch specific.
Changelog:
- fix the x86-64 idle notifier to cover all re-entries into the
core idle loop after an interrupt.
- define enter_idle/exit_idle in idle.h to avoid branching when
not needed
Signed-off-by: Stephane Eranian <eranain@....hp.com>
diff --git a/arch/i386/kernel/apic.c b/arch/i386/kernel/apic.c
--- a/arch/i386/kernel/apic.c
+++ b/arch/i386/kernel/apic.c
@@ -1230,9 +1230,11 @@ fastcall void smp_apic_timer_interrupt(s
* Besides, if we don't timer interrupts ignore the global
* interrupt lock, which is the WrongThing (tm) to do.
*/
+ exit_idle();
irq_enter();
smp_local_timer_interrupt(regs);
irq_exit();
+ enter_idle();
}
#ifndef CONFIG_SMP
@@ -1279,6 +1281,7 @@ fastcall void smp_spurious_interrupt(str
{
unsigned long v;
+ exit_idle();
irq_enter();
/*
* Check if this really is a spurious interrupt and ACK it
@@ -1293,6 +1296,7 @@ fastcall void smp_spurious_interrupt(str
printk(KERN_INFO "spurious APIC interrupt on CPU#%d, should never happen.\n",
smp_processor_id());
irq_exit();
+ enter_idle();
}
/*
@@ -1303,6 +1307,7 @@ fastcall void smp_error_interrupt(struct
{
unsigned long v, v1;
+ exit_idle();
irq_enter();
/* First tickle the hardware, only then report what went on. -- REW */
v = apic_read(APIC_ESR);
@@ -1324,6 +1329,7 @@ fastcall void smp_error_interrupt(struct
printk (KERN_DEBUG "APIC error on CPU%d: %02lx(%02lx)\n",
smp_processor_id(), v , v1);
irq_exit();
+ enter_idle();
}
/*
diff --git a/arch/i386/kernel/cpu/mcheck/p4.c b/arch/i386/kernel/cpu/mcheck/p4.c
--- a/arch/i386/kernel/cpu/mcheck/p4.c
+++ b/arch/i386/kernel/cpu/mcheck/p4.c
@@ -70,9 +70,11 @@ static void (*vendor_thermal_interrupt)(
fastcall void smp_thermal_interrupt(struct pt_regs *regs)
{
+ exit_idle();
irq_enter();
vendor_thermal_interrupt(regs);
irq_exit();
+ enter_idle();
}
/* P4/Xeon Thermal regulation detect and init */
diff --git a/arch/i386/kernel/process.c b/arch/i386/kernel/process.c
--- a/arch/i386/kernel/process.c
+++ b/arch/i386/kernel/process.c
@@ -78,6 +78,35 @@ void (*pm_idle)(void);
EXPORT_SYMBOL(pm_idle);
static DEFINE_PER_CPU(unsigned int, cpu_idle_state);
+static ATOMIC_NOTIFIER_HEAD(idle_notifier);
+
+void idle_notifier_register(struct notifier_block *n)
+{
+ atomic_notifier_chain_register(&idle_notifier, n);
+}
+EXPORT_SYMBOL_GPL(idle_notifier_register);
+
+void idle_notifier_unregister(struct notifier_block *n)
+{
+ atomic_notifier_chain_unregister(&idle_notifier, 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;
+ atomic_notifier_call_chain(&idle_notifier, IDLE_START, NULL);
+}
+
+void __exit_idle(void)
+{
+ __get_cpu_var(idle_state) = CPU_NOT_IDLE;
+ atomic_notifier_call_chain(&idle_notifier, IDLE_END, NULL);
+}
+
void disable_hlt(void)
{
hlt_counter++;
@@ -193,7 +222,9 @@ void cpu_idle(void)
play_dead();
__get_cpu_var(irq_stat).idle_timestamp = jiffies;
+ __enter_idle();
idle();
+ __exit_idle();
}
preempt_enable_no_resched();
schedule();
diff --git a/arch/i386/kernel/smp.c b/arch/i386/kernel/smp.c
--- a/arch/i386/kernel/smp.c
+++ b/arch/i386/kernel/smp.c
@@ -624,6 +624,7 @@ fastcall void smp_call_function_interrup
/*
* At this point the info structure may be out of scope unless wait==1
*/
+ exit_idle();
irq_enter();
(*func)(info);
irq_exit();
@@ -632,5 +633,6 @@ fastcall void smp_call_function_interrup
mb();
atomic_inc(&call_data->finished);
}
+ enter_idle();
}
diff --git a/arch/x86_64/kernel/apic.c b/arch/x86_64/kernel/apic.c
--- a/arch/x86_64/kernel/apic.c
+++ b/arch/x86_64/kernel/apic.c
@@ -988,6 +988,7 @@ void smp_apic_timer_interrupt(struct pt_
irq_enter();
smp_local_timer_interrupt(regs);
irq_exit();
+ enter_idle();
}
/*
@@ -1069,6 +1070,7 @@ asmlinkage void smp_spurious_interrupt(v
}
#endif
irq_exit();
+ enter_idle();
}
/*
@@ -1101,6 +1103,7 @@ asmlinkage void smp_error_interrupt(void
printk (KERN_DEBUG "APIC error on CPU%d: %02x(%02x)\n",
smp_processor_id(), v , v1);
irq_exit();
+ enter_idle();
}
int disable_apic;
diff --git a/arch/x86_64/kernel/irq.c b/arch/x86_64/kernel/irq.c
--- a/arch/x86_64/kernel/irq.c
+++ b/arch/x86_64/kernel/irq.c
@@ -131,6 +131,7 @@ asmlinkage unsigned int do_IRQ(struct pt
#endif
__do_IRQ(irq, regs);
irq_exit();
+ enter_idle();
return 1;
}
diff --git a/arch/x86_64/kernel/mce_amd.c b/arch/x86_64/kernel/mce_amd.c
--- a/arch/x86_64/kernel/mce_amd.c
+++ b/arch/x86_64/kernel/mce_amd.c
@@ -224,6 +224,7 @@ asmlinkage void mce_threshold_interrupt(
}
out:
irq_exit();
+ enter_idle();
}
/*
diff --git a/arch/x86_64/kernel/mce_intel.c b/arch/x86_64/kernel/mce_intel.c
--- a/arch/x86_64/kernel/mce_intel.c
+++ b/arch/x86_64/kernel/mce_intel.c
@@ -42,6 +42,7 @@ asmlinkage void smp_thermal_interrupt(vo
mce_log(&m);
done:
irq_exit();
+ enter_idle();
}
static void __cpuinit intel_init_thermal(struct cpuinfo_x86 *c)
diff --git a/arch/x86_64/kernel/process.c b/arch/x86_64/kernel/process.c
--- a/arch/x86_64/kernel/process.c
+++ b/arch/x86_64/kernel/process.c
@@ -83,26 +83,18 @@ 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)
+void __enter_idle(void)
{
__get_cpu_var(idle_state) = CPU_IDLE;
atomic_notifier_call_chain(&idle_notifier, IDLE_START, NULL);
}
-static void __exit_idle(void)
+void __exit_idle(void)
{
__get_cpu_var(idle_state) = CPU_NOT_IDLE;
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))
- return;
- __exit_idle();
-}
-
/*
* We use this if we don't have any better
* idle routine..
@@ -218,7 +210,7 @@ void cpu_idle (void)
idle = default_idle;
if (cpu_is_offline(smp_processor_id()))
play_dead();
- enter_idle();
+ __enter_idle();
idle();
__exit_idle();
}
diff --git a/arch/x86_64/kernel/smp.c b/arch/x86_64/kernel/smp.c
--- a/arch/x86_64/kernel/smp.c
+++ b/arch/x86_64/kernel/smp.c
@@ -520,6 +520,7 @@ asmlinkage void smp_call_function_interr
mb();
atomic_inc(&call_data->finished);
}
+ enter_idle();
}
int safe_smp_processor_id(void)
diff --git a/include/asm-x86_64/idle.h b/include/asm-x86_64/idle.h
--- a/include/asm-x86_64/idle.h
+++ b/include/asm-x86_64/idle.h
@@ -8,7 +8,25 @@ struct notifier_block;
void idle_notifier_register(struct notifier_block *n);
void idle_notifier_unregister(struct notifier_block *n);
-void enter_idle(void);
-void exit_idle(void);
+void __exit_idle(void);
+void __enter_idle(void);
+
+/* Called from interrupts to signify back to idle */
+static inline void enter_idle(void)
+{
+ /* bitwise or is intentional */
+ if (current->pid | read_pda(irqcount))
+ return;
+ __enter_idle();
+}
+
+/* Called from interrupts to signify idle end */
+static inline void exit_idle(void)
+{
+ /* bitwise or is intentional */
+ if (current->pid | read_pda(irqcount))
+ return;
+ __exit_idle();
+}
#endif
-
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