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Date: Wed, 8 Sep 2010 11:59:54 -0400
From: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
To: linux-kernel@...r.kernel.org
Cc: ltt-dev@...ts.casi.polymtl.ca,
Linus Torvalds <torvalds@...ux-foundation.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Ingo Molnar <mingo@...e.hu>,
Peter Zijlstra <peterz@...radead.org>,
Steven Rostedt <rostedt@...dmis.org>,
Frederic Weisbecker <fweisbec@...il.com>,
Thomas Gleixner <tglx@...utronix.de>,
Li Zefan <lizf@...fujitsu.com>,
Lai Jiangshan <laijs@...fujitsu.com>,
Johannes Berg <johannes.berg@...el.com>,
Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
Arnaldo Carvalho de Melo <acme@...radead.org>,
Tom Zanussi <tzanussi@...il.com>,
KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
Andi Kleen <andi@...stfloor.org>
Subject: [RFC PATCH 2/2] Idle notifier standardization x86_32 (v2)
Add idle notifier callback to x86_32.
Changelog since v1:
* Add CONFIG_HAVE_IDLE_NOTIFIER.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
---
arch/x86/Kconfig | 2 +-
arch/x86/include/asm/idle.h | 5 -----
arch/x86/kernel/apm_32.c | 6 ++++++
arch/x86/kernel/process_32.c | 33 +++++++++++++++++++++++++++++++++
4 files changed, 40 insertions(+), 6 deletions(-)
Index: linux.trees.git/arch/x86/kernel/process_32.c
===================================================================
--- linux.trees.git.orig/arch/x86/kernel/process_32.c
+++ linux.trees.git/arch/x86/kernel/process_32.c
@@ -38,6 +38,8 @@
#include <linux/uaccess.h>
#include <linux/io.h>
#include <linux/kdebug.h>
+#include <linux/notifier.h>
+#include <linux/idle.h>
#include <asm/pgtable.h>
#include <asm/system.h>
@@ -61,6 +63,30 @@
asmlinkage void ret_from_fork(void) __asm__("ret_from_fork");
+static DEFINE_PER_CPU(unsigned char, is_idle);
+
+void enter_idle(void)
+{
+ percpu_write(is_idle, 1);
+ notify_idle(IDLE_START);
+}
+
+static void __exit_idle(void)
+{
+ if (x86_test_and_clear_bit_percpu(0, is_idle) == 0)
+ return;
+ notify_idle(IDLE_END);
+}
+
+/* Called from interrupts to signify idle end */
+void exit_idle(void)
+{
+ /* idle loop has pid 0 */
+ if (current->pid)
+ return;
+ __exit_idle();
+}
+
/*
* Return saved PC of a blocked thread.
*/
@@ -109,10 +135,17 @@ void cpu_idle(void)
play_dead();
local_irq_disable();
+ enter_idle();
/* Don't trace irqs off for idle */
stop_critical_timings();
pm_idle();
start_critical_timings();
+ /*
+ * 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();
trace_power_end(smp_processor_id());
}
Index: linux.trees.git/arch/x86/include/asm/idle.h
===================================================================
--- linux.trees.git.orig/arch/x86/include/asm/idle.h
+++ linux.trees.git/arch/x86/include/asm/idle.h
@@ -1,13 +1,8 @@
#ifndef _ASM_X86_IDLE_H
#define _ASM_X86_IDLE_H
-#ifdef CONFIG_X86_64
void enter_idle(void);
void exit_idle(void);
-#else /* !CONFIG_X86_64 */
-static inline void enter_idle(void) { }
-static inline void exit_idle(void) { }
-#endif /* CONFIG_X86_64 */
void c1e_remove_cpu(int cpu);
Index: linux.trees.git/arch/x86/kernel/apm_32.c
===================================================================
--- linux.trees.git.orig/arch/x86/kernel/apm_32.c
+++ linux.trees.git/arch/x86/kernel/apm_32.c
@@ -227,6 +227,7 @@
#include <linux/suspend.h>
#include <linux/kthread.h>
#include <linux/jiffies.h>
+#include <linux/idle.h>
#include <asm/system.h>
#include <asm/uaccess.h>
@@ -947,10 +948,15 @@ recalc:
break;
}
}
+ enter_idle();
if (original_pm_idle)
original_pm_idle();
else
default_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();
local_irq_disable();
jiffies_since_last_check = jiffies - last_jiffies;
if (jiffies_since_last_check > idle_period)
Index: linux.trees.git/arch/x86/Kconfig
===================================================================
--- linux.trees.git.orig/arch/x86/Kconfig
+++ linux.trees.git/arch/x86/Kconfig
@@ -45,7 +45,7 @@ config X86
select HAVE_ARCH_TRACEHOOK
select HAVE_GENERIC_DMA_COHERENT if X86_32
select HAVE_EFFICIENT_UNALIGNED_ACCESS
- select HAVE_IDLE_NOTIFIER if X86_64
+ select HAVE_IDLE_NOTIFIER
select USER_STACKTRACE_SUPPORT
select HAVE_REGS_AND_STACK_ACCESS_API
select HAVE_DMA_API_DEBUG
--
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com
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