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Message-ID: <tip-d166991234347215dc23fc9dc15a63a83a1a54e1@git.kernel.org>
Date: Mon, 8 Apr 2013 13:14:03 -0700
From: tip-bot for Thomas Gleixner <tipbot@...or.com>
To: linux-tip-commits@...r.kernel.org
Cc: linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...nel.org,
rusty@...tcorp.com.au, torvalds@...ux-foundation.org,
peterz@...radead.org, srivatsa.bhat@...ux.vnet.ibm.com,
paulmck@...ux.vnet.ibm.com, tglx@...utronix.de,
magnus.damm@...il.com
Subject: [tip:smp/hotplug] idle: Implement generic idle function
Commit-ID: d166991234347215dc23fc9dc15a63a83a1a54e1
Gitweb: http://git.kernel.org/tip/d166991234347215dc23fc9dc15a63a83a1a54e1
Author: Thomas Gleixner <tglx@...utronix.de>
AuthorDate: Thu, 21 Mar 2013 22:49:35 +0100
Committer: Thomas Gleixner <tglx@...utronix.de>
CommitDate: Mon, 8 Apr 2013 17:39:23 +0200
idle: Implement generic idle function
All idle functions in arch/* are more or less the same, plus minus a
few bugs and extra instrumentation, tickless support and other
optional items.
Implement a generic idle function which resembles the functionality
found in arch/. Provide weak arch_cpu_idle_* functions which can be
overridden by the architecture code if needed.
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Rusty Russell <rusty@...tcorp.com.au>
Cc: Paul McKenney <paulmck@...ux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Reviewed-by: Cc: Srivatsa S. Bhat <srivatsa.bhat@...ux.vnet.ibm.com>
Cc: Magnus Damm <magnus.damm@...il.com>
Link: http://lkml.kernel.org/r/20130321215233.646635455@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---
arch/Kconfig | 3 ++
include/linux/cpu.h | 8 ++++
kernel/cpu/idle.c | 105 ++++++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 116 insertions(+)
diff --git a/arch/Kconfig b/arch/Kconfig
index 1455579..a699f37 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -216,6 +216,9 @@ config USE_GENERIC_SMP_HELPERS
config GENERIC_SMP_IDLE_THREAD
bool
+config GENERIC_IDLE_LOOP
+ bool
+
# Select if arch init_task initializer is different to init/init_task.c
config ARCH_INIT_TASK
bool
diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index 7419e30..c6f6e08 100644
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -220,4 +220,12 @@ enum cpuhp_state {
void cpu_startup_entry(enum cpuhp_state state);
void cpu_idle(void);
+void cpu_idle_poll_ctrl(bool enable);
+
+void arch_cpu_idle(void);
+void arch_cpu_idle_prepare(void);
+void arch_cpu_idle_enter(void);
+void arch_cpu_idle_exit(void);
+void arch_cpu_idle_dead(void);
+
#endif /* _LINUX_CPU_H_ */
diff --git a/kernel/cpu/idle.c b/kernel/cpu/idle.c
index 1908f00..54c3203 100644
--- a/kernel/cpu/idle.c
+++ b/kernel/cpu/idle.c
@@ -3,8 +3,113 @@
*/
#include <linux/sched.h>
#include <linux/cpu.h>
+#include <linux/tick.h>
+#include <linux/mm.h>
+#include <asm/tlb.h>
+
+#include <trace/events/power.h>
+
+#ifndef CONFIG_GENERIC_IDLE_LOOP
void cpu_startup_entry(enum cpuhp_state state)
{
cpu_idle();
}
+#else
+
+static int __read_mostly cpu_idle_force_poll;
+
+void cpu_idle_poll_ctrl(bool enable)
+{
+ if (enable) {
+ cpu_idle_force_poll++;
+ } else {
+ cpu_idle_force_poll--;
+ WARN_ON_ONCE(cpu_idle_force_poll < 0);
+ }
+}
+
+#ifdef CONFIG_GENERIC_IDLE_POLL_SETUP
+static int __init cpu_idle_poll_setup(char *__unused)
+{
+ cpu_idle_force_poll = 1;
+ return 1;
+}
+__setup("nohlt", cpu_idle_poll_setup);
+
+static int __init cpu_idle_nopoll_setup(char *__unused)
+{
+ cpu_idle_force_poll = 0;
+ return 1;
+}
+__setup("hlt", cpu_idle_nopoll_setup);
+#endif
+
+static inline int cpu_idle_poll(void)
+{
+ trace_cpu_idle_rcuidle(0, smp_processor_id());
+ local_irq_enable();
+ while (!need_resched())
+ cpu_relax();
+ trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, smp_processor_id());
+ return 1;
+}
+
+/* Weak implementations for optional arch specific functions */
+void __weak arch_cpu_idle_prepare(void) { }
+void __weak arch_cpu_idle_enter(void) { }
+void __weak arch_cpu_idle_exit(void) { }
+void __weak arch_cpu_idle_dead(void) { }
+void __weak arch_cpu_idle(void)
+{
+ cpu_idle_force_poll = 1;
+}
+
+/*
+ * Generic idle loop implementation
+ */
+static void cpu_idle_loop(void)
+{
+ while (1) {
+ tick_nohz_idle_enter();
+
+ while (!need_resched()) {
+ check_pgt_cache();
+ rmb();
+
+ if (cpu_is_offline(smp_processor_id()))
+ arch_cpu_idle_dead();
+
+ local_irq_disable();
+ arch_cpu_idle_enter();
+
+ if (cpu_idle_force_poll) {
+ cpu_idle_poll();
+ } else {
+ current_clr_polling();
+ if (!need_resched()) {
+ stop_critical_timings();
+ rcu_idle_enter();
+ arch_cpu_idle();
+ WARN_ON_ONCE(irqs_disabled());
+ rcu_idle_exit();
+ start_critical_timings();
+ } else {
+ local_irq_enable();
+ }
+ current_set_polling();
+ }
+ arch_cpu_idle_exit();
+ }
+ tick_nohz_idle_exit();
+ schedule_preempt_disabled();
+ }
+}
+
+void cpu_startup_entry(enum cpuhp_state state)
+{
+ current_set_polling();
+ arch_cpu_idle_prepare();
+ cpu_idle_loop();
+}
+#endif
--
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