The patch titled
high-res timers: allow TSC clocksource if pmtimer present
has been added to the -mm tree. Its filename is
high-res-timers-allow-tsc-clocksource-if-pmtimer-present.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: high-res timers: allow TSC clocksource if pmtimer present
From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
allow TSC clocksource dependent on the existence of pmtimer as a fallback,
to resync across TSC-destructive resume/halt/cpufreq events.
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
arch/i386/kernel/tsc.c | 47 +++++++++++++++++++++++++++--------
include/linux/acpi_pmtmr.h | 2 +
2 files changed, 39 insertions(+), 10 deletions(-)
diff -puN arch/i386/kernel/tsc.c~high-res-timers-allow-tsc-clocksource-if-pmtimer-present arch/i386/kernel/tsc.c
--- a/arch/i386/kernel/tsc.c~high-res-timers-allow-tsc-clocksource-if-pmtimer-present
+++ a/arch/i386/kernel/tsc.c
@@ -10,6 +10,7 @@
#include <linux/jiffies.h>
#include <linux/init.h>
#include <linux/dmi.h>
+#include <linux/acpi_pmtmr.h>
#include <asm/delay.h>
#include <asm/tsc.h>
@@ -386,44 +387,55 @@ static struct dmi_system_id __initdata b
{}
};
-#define TSC_FREQ_CHECK_INTERVAL (10*MSEC_PER_SEC) /* 10sec in MS */
+#define TSC_FREQ_CHECK_INTERVAL MSEC_PER_SEC
static struct timer_list verify_tsc_freq_timer;
+static unsigned long pm_multiplier;
/* XXX - Probably should add locking */
static void verify_tsc_freq(unsigned long unused)
{
static u64 last_tsc;
- static unsigned long last_jiffies;
-
- u64 now_tsc, interval_tsc;
- unsigned long now_jiffies, interval_jiffies;
+ static unsigned long last_jiffies, last_pm;
+ u64 now_tsc, interval_tsc, tmp;
+ unsigned long now_jiffies, interval_jiffies, pm, pm_delta;
if (check_tsc_unstable())
return;
rdtscll(now_tsc);
now_jiffies = jiffies;
+ pm = acpi_pm_read_early();
- if (!last_jiffies) {
+ if (!last_jiffies)
goto out;
- }
- interval_jiffies = now_jiffies - last_jiffies;
interval_tsc = now_tsc - last_tsc;
interval_tsc *= HZ;
do_div(interval_tsc, cpu_khz*1000);
+ if (pm == last_pm) {
+ interval_jiffies = now_jiffies - last_jiffies;
+ } else {
+ if (pm < last_pm)
+ pm_delta = (pm + ACPI_PM_OVRRUN) - last_pm;
+ else
+ pm_delta = pm - last_pm;
+ tmp = (((u64) pm_delta) * pm_multiplier) >> 22;
+ do_div(tmp, (NSEC_PER_SEC/HZ));
+ interval_jiffies = (unsigned long) tmp;
+ }
+
if (interval_tsc < (interval_jiffies * 3 / 4)) {
printk("TSC appears to be running slowly. "
- "Marking it as unstable\n");
+ "Marking it as unstable\n");
mark_tsc_unstable();
return;
}
-
out:
last_tsc = now_tsc;
last_jiffies = now_jiffies;
+ last_pm = pm;
/* set us up to go off on the next interval: */
mod_timer(&verify_tsc_freq_timer,
jiffies + msecs_to_jiffies(TSC_FREQ_CHECK_INTERVAL));
@@ -462,6 +474,21 @@ static int __init init_tsc_clocksource(v
if (check_tsc_unstable())
clocksource_tsc.rating = 0;
+ /*
+ * Mark TSC unsuitable for high resolution timers, when
+ * pm_timer is not available as a fallback. TSC has so many
+ * pitfalls: frequency changes, stop in idle ... When we
+ * switch to high resolution mode we can not longer detect a
+ * firmware caused frequency change, as the emulated tick uses
+ * TSC as reference. This results in a circular dependency.
+ * Switch only to high resolution mode, if pm_timer or such is
+ * available.
+ */
+ if (!pmtmr_ioport || !clocksource_tsc.rating)
+ clocksource_tsc.is_continuous = 0;
+
+ pm_multiplier = clocksource_hz2mult(PMTMR_TICKS_PER_SEC, 22);
+
init_timer(&verify_tsc_freq_timer);
verify_tsc_freq_timer.function = verify_tsc_freq;
verify_tsc_freq_timer.expires =
diff -puN include/linux/acpi_pmtmr.h~high-res-timers-allow-tsc-clocksource-if-pmtimer-present include/linux/acpi_pmtmr.h
--- a/include/linux/acpi_pmtmr.h~high-res-timers-allow-tsc-clocksource-if-pmtimer-present
+++ a/include/linux/acpi_pmtmr.h
@@ -27,6 +27,8 @@ static inline u32 acpi_pm_read_early(voi
#else
+#define pmtmr_ioport 0
+
static inline u32 acpi_pm_read_early(void)
{
return 0;
_
Patches currently in -mm which might be from tglx@xxxxxxxxxxxxx are
origin.patch
git-mtd.patch
gtod-uninline-jiffiesh.patch
gtod-fix-multiple-conversion-bugs-in-msecs_to_jiffies.patch
gtod-fix-timeout-overflow.patch
gtod-persistent-clock-support-core.patch
gtod-persistent-clock-support-i386.patch
dynticks-uninline-irq_enter.patch
dynticks-extend-next_timer_interrupt-to-use-a-reference-jiffie.patch
hrtimers-namespace-and-enum-cleanup.patch
hrtimers-clean-up-locking.patch
hrtimers-add-state-tracking.patch
hrtimers-clean-up-callback-tracking.patch
hrtimers-move-and-add-documentation.patch
acpi-include-fix.patch
acpi-keep-track-of-timer-broadcast.patch
acpi-add-state-propagation-for-dynamic-broadcasting.patch
acpi-cleanups-allow-early-access-to-pmtimer.patch
i386-apic-clean-up-the-apic-code.patch
clockevents-core.patch
clockevents-i386-drivers.patch
clockevents-i386-hpet-driver.patch
i386-apic-rework-and-fix-local-apic-calibration.patch
high-res-timers-core.patch
high-res-timers-core-do-itimer-rearming-in-process-context.patch
high-res-timers-allow-tsc-clocksource-if-pmtimer-present.patch
dynticks-core.patch
dynticks-add-nohz-stats-to-proc-stat.patch
dynticks-i386-support-idle-handler-callbacks.patch
dynticks-i386-prepare-nmi-watchdog.patch
high-res-timers-dynticks-i386-support-enable-in-kconfig.patch
debugging-feature-add-proc-timer_stat.patch
-
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