x86: idle wakeup event in the HLT loop

do a proper idle-wakeup event on HLT as well - some CPUs stop the TSC
in HLT too, not just when going through the ACPI methods.

(the ACPI idle code already does this.)

[ update the 64-bit side too, as noticed by Jiri Slaby. ]

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index 46d391d..a63d2d2 100644 (file)
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -113,10 +113,19 @@ void default_idle(void)
                smp_mb();
 
                local_irq_disable();
-               if (!need_resched())
+               if (!need_resched()) {
+                       ktime_t t0, t1;
+                       u64 t0n, t1n;
+
+                       t0 = ktime_get();
+                       t0n = ktime_to_ns(t0);
                        safe_halt();    /* enables interrupts racelessly */
-               else
-                       local_irq_enable();
+                       local_irq_disable();
+                       t1 = ktime_get();
+                       t1n = ktime_to_ns(t1);
+                       sched_clock_idle_wakeup_event(t1n - t0n);
+               }
+               local_irq_enable();
                current_thread_info()->status |= TS_POLLING;
        } else {
                /* loop is done by the caller */

diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index c2db7ef..40fed47 100644 (file)
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -116,9 +116,16 @@ static void default_idle(void)
        smp_mb();
        local_irq_disable();
        if (!need_resched()) {
-               /* Enables interrupts one instruction before HLT.
-                  x86 special cases this so there is no race. */
-               safe_halt();
+               ktime_t t0, t1;
+               u64 t0n, t1n;
+
+               t0 = ktime_get();
+               t0n = ktime_to_ns(t0);
+               safe_halt();    /* enables interrupts racelessly */
+               local_irq_disable();
+               t1 = ktime_get();
+               t1n = ktime_to_ns(t1);
+               sched_clock_idle_wakeup_event(t1n - t0n);
        } else
                local_irq_enable();
        current_thread_info()->status |= TS_POLLING;