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-rw-r--r--arch/x86/kernel/tsc.c98
1 files changed, 92 insertions, 6 deletions
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 0c40d8b7241..823f79a17ad 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -659,7 +659,7 @@ void restore_sched_clock_state(void)
local_irq_save(flags);
- __get_cpu_var(cyc2ns_offset) = 0;
+ __this_cpu_write(cyc2ns_offset, 0);
offset = cyc2ns_suspend - sched_clock();
for_each_possible_cpu(cpu)
@@ -872,6 +872,9 @@ __cpuinit int unsynchronized_tsc(void)
if (boot_cpu_has(X86_FEATURE_CONSTANT_TSC))
return 0;
+
+ if (tsc_clocksource_reliable)
+ return 0;
/*
* Intel systems are normally all synchronized.
* Exceptions must mark TSC as unstable:
@@ -879,14 +882,92 @@ __cpuinit int unsynchronized_tsc(void)
if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL) {
/* assume multi socket systems are not synchronized: */
if (num_possible_cpus() > 1)
- tsc_unstable = 1;
+ return 1;
}
- return tsc_unstable;
+ return 0;
+}
+
+
+static void tsc_refine_calibration_work(struct work_struct *work);
+static DECLARE_DELAYED_WORK(tsc_irqwork, tsc_refine_calibration_work);
+/**
+ * tsc_refine_calibration_work - Further refine tsc freq calibration
+ * @work - ignored.
+ *
+ * This functions uses delayed work over a period of a
+ * second to further refine the TSC freq value. Since this is
+ * timer based, instead of loop based, we don't block the boot
+ * process while this longer calibration is done.
+ *
+ * If there are any calibration anomolies (too many SMIs, etc),
+ * or the refined calibration is off by 1% of the fast early
+ * calibration, we throw out the new calibration and use the
+ * early calibration.
+ */
+static void tsc_refine_calibration_work(struct work_struct *work)
+{
+ static u64 tsc_start = -1, ref_start;
+ static int hpet;
+ u64 tsc_stop, ref_stop, delta;
+ unsigned long freq;
+
+ /* Don't bother refining TSC on unstable systems */
+ if (check_tsc_unstable())
+ goto out;
+
+ /*
+ * Since the work is started early in boot, we may be
+ * delayed the first time we expire. So set the workqueue
+ * again once we know timers are working.
+ */
+ if (tsc_start == -1) {
+ /*
+ * Only set hpet once, to avoid mixing hardware
+ * if the hpet becomes enabled later.
+ */
+ hpet = is_hpet_enabled();
+ schedule_delayed_work(&tsc_irqwork, HZ);
+ tsc_start = tsc_read_refs(&ref_start, hpet);
+ return;
+ }
+
+ tsc_stop = tsc_read_refs(&ref_stop, hpet);
+
+ /* hpet or pmtimer available ? */
+ if (!hpet && !ref_start && !ref_stop)
+ goto out;
+
+ /* Check, whether the sampling was disturbed by an SMI */
+ if (tsc_start == ULLONG_MAX || tsc_stop == ULLONG_MAX)
+ goto out;
+
+ delta = tsc_stop - tsc_start;
+ delta *= 1000000LL;
+ if (hpet)
+ freq = calc_hpet_ref(delta, ref_start, ref_stop);
+ else
+ freq = calc_pmtimer_ref(delta, ref_start, ref_stop);
+
+ /* Make sure we're within 1% */
+ if (abs(tsc_khz - freq) > tsc_khz/100)
+ goto out;
+
+ tsc_khz = freq;
+ printk(KERN_INFO "Refined TSC clocksource calibration: "
+ "%lu.%03lu MHz.\n", (unsigned long)tsc_khz / 1000,
+ (unsigned long)tsc_khz % 1000);
+
+out:
+ clocksource_register_khz(&clocksource_tsc, tsc_khz);
}
-static void __init init_tsc_clocksource(void)
+
+static int __init init_tsc_clocksource(void)
{
+ if (!cpu_has_tsc || tsc_disabled > 0 || !tsc_khz)
+ return 0;
+
if (tsc_clocksource_reliable)
clocksource_tsc.flags &= ~CLOCK_SOURCE_MUST_VERIFY;
/* lower the rating if we already know its unstable: */
@@ -894,8 +975,14 @@ static void __init init_tsc_clocksource(void)
clocksource_tsc.rating = 0;
clocksource_tsc.flags &= ~CLOCK_SOURCE_IS_CONTINUOUS;
}
- clocksource_register_khz(&clocksource_tsc, tsc_khz);
+ schedule_delayed_work(&tsc_irqwork, 0);
+ return 0;
}
+/*
+ * We use device_initcall here, to ensure we run after the hpet
+ * is fully initialized, which may occur at fs_initcall time.
+ */
+device_initcall(init_tsc_clocksource);
void __init tsc_init(void)
{
@@ -949,6 +1036,5 @@ void __init tsc_init(void)
mark_tsc_unstable("TSCs unsynchronized");
check_system_tsc_reliable();
- init_tsc_clocksource();
}