x86: Use generic idle loop

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Cc: Magnus Damm <magnus.damm@gmail.com>
Link: http://lkml.kernel.org/r/20130321215235.486594473@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: x86@kernel.org

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 70c0f3d..422a72b 100644 (file)
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -97,6 +97,7 @@ config X86
        select GENERIC_IOMAP
        select DCACHE_WORD_ACCESS
        select GENERIC_SMP_IDLE_THREAD
+       select GENERIC_IDLE_LOOP
        select ARCH_WANT_IPC_PARSE_VERSION if X86_32
        select HAVE_ARCH_SECCOMP_FILTER
        select BUILDTIME_EXTABLE_SORT

diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 14ae100..6833bff 100644 (file)
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -301,13 +301,7 @@ void exit_idle(void)
 }
 #endif
 
-/*
- * The idle thread. There's no useful work to be
- * done, so just try to conserve power and have a
- * low exit latency (ie sit in a loop waiting for
- * somebody to say that they'd like to reschedule)
- */
-void cpu_idle(void)
+void arch_cpu_idle_prepare(void)
 {
        /*
         * If we're the non-boot CPU, nothing set the stack canary up
@@ -317,71 +311,40 @@ void cpu_idle(void)
         * canaries already on the stack wont ever trigger).
         */
        boot_init_stack_canary();
-       current_thread_info()->status |= TS_POLLING;
-
-       while (1) {
-               tick_nohz_idle_enter();
-
-               while (!need_resched()) {
-                       rmb();
-
-                       if (cpu_is_offline(smp_processor_id()))
-                               play_dead();
-
-                       /*
-                        * Idle routines should keep interrupts disabled
-                        * from here on, until they go to idle.
-                        * Otherwise, idle callbacks can misfire.
-                        */
-                       local_touch_nmi();
-                       local_irq_disable();
-
-                       enter_idle();
-
-                       /* Don't trace irqs off for idle */
-                       stop_critical_timings();
-
-                       /* enter_idle() needs rcu for notifiers */
-                       rcu_idle_enter();
+}
 
-                       if (cpuidle_idle_call())
-                               x86_idle();
+void arch_cpu_idle_enter(void)
+{
+       local_touch_nmi();
+       enter_idle();
+}
 
-                       rcu_idle_exit();
-                       start_critical_timings();
+void arch_cpu_idle_exit(void)
+{
+       __exit_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();
-               }
+void arch_cpu_idle_dead(void)
+{
+       play_dead();
+}
 
-               tick_nohz_idle_exit();
-               preempt_enable_no_resched();
-               schedule();
-               preempt_disable();
-       }
+/*
+ * Called from the generic idle code.
+ */
+void arch_cpu_idle(void)
+{
+       if (cpuidle_idle_call())
+               x86_idle();
 }
 
 /*
- * We use this if we don't have any better
- * idle routine..
+ * We use this if we don't have any better idle routine..
  */
 void default_idle(void)
 {
        trace_cpu_idle_rcuidle(1, smp_processor_id());
-       current_thread_info()->status &= ~TS_POLLING;
-       /*
-        * TS_POLLING-cleared state must be visible before we
-        * test NEED_RESCHED:
-        */
-       smp_mb();
-
-       if (!need_resched())
-               safe_halt();    /* enables interrupts racelessly */
-       else
-               local_irq_enable();
-       current_thread_info()->status |= TS_POLLING;
+       safe_halt();
        trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, smp_processor_id());
 }
 #ifdef CONFIG_APM_MODULE
@@ -411,20 +374,6 @@ void stop_this_cpu(void *dummy)
                halt();
 }
 
-/*
- * On SMP it's slightly faster (but much more power-consuming!)
- * to poll the ->work.need_resched flag instead of waiting for the
- * cross-CPU IPI to arrive. Use this option with caution.
- */
-static void poll_idle(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());
-}
-
 bool amd_e400_c1e_detected;
 EXPORT_SYMBOL(amd_e400_c1e_detected);
 
@@ -489,10 +438,10 @@ static void amd_e400_idle(void)
 void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c)
 {
 #ifdef CONFIG_SMP
-       if (x86_idle == poll_idle && smp_num_siblings > 1)
+       if (boot_option_idle_override == IDLE_POLL && smp_num_siblings > 1)
                pr_warn_once("WARNING: polling idle and HT enabled, performance may degrade\n");
 #endif
-       if (x86_idle)
+       if (x86_idle || boot_option_idle_override == IDLE_POLL)
                return;
 
        if (cpu_has_amd_erratum(amd_erratum_400)) {
@@ -517,8 +466,8 @@ static int __init idle_setup(char *str)
 
        if (!strcmp(str, "poll")) {
                pr_info("using polling idle threads\n");
-               x86_idle = poll_idle;
                boot_option_idle_override = IDLE_POLL;
+               cpu_idle_poll_ctrl(true);
        } else if (!strcmp(str, "halt")) {
                /*
                 * When the boot option of idle=halt is added, halt is

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 9f190a2..9c73b51 100644 (file)
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -284,7 +284,7 @@ notrace static void __cpuinit start_secondary(void *unused)
        x86_cpuinit.setup_percpu_clockev();
 
        wmb();
-       cpu_idle();
+       cpu_startup_entry(CPUHP_ONLINE);
 }
 
 void __init smp_store_boot_cpu_info(void)

diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c
index 09ea61d..73642e9 100644 (file)
--- a/arch/x86/xen/smp.c
+++ b/arch/x86/xen/smp.c
@@ -95,7 +95,7 @@ static void __cpuinit cpu_bringup(void)
 static void __cpuinit cpu_bringup_and_idle(void)
 {
        cpu_bringup();
-       cpu_idle();
+       cpu_startup_entry(CPUHP_ONLINE);
 }
 
 static int xen_smp_intr_init(unsigned int cpu)