The patch titled
GTOD: Mark TSC unusable for highres timers
has been removed from the -mm tree. Its filename was
gtod-mark-tsc-unusable-for-highres-timers.patch
This patch was dropped because an updated version will be merged
------------------------------------------------------
Subject: GTOD: Mark TSC unusable for highres timers
From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
The TSC is too unstable and unreliable to be used with high resolution timers.
The automatic detection of TSC unstability fails once we switched to high
resolution mode, because the tick emulation would use the TSC as reference.
This results in a circular dependency. Mark it unusable for high res upfront.
[akpm@xxxxxxxx: updated for i386-time-avoid-pit-smp-lockups.patch]
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
Cc: john stultz <johnstul@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
arch/i386/kernel/tsc.c | 15 ++++++++++++++-
1 files changed, 14 insertions(+), 1 deletion(-)
diff -puN arch/i386/kernel/tsc.c~gtod-mark-tsc-unusable-for-highres-timers arch/i386/kernel/tsc.c
--- a/arch/i386/kernel/tsc.c~gtod-mark-tsc-unusable-for-highres-timers
+++ a/arch/i386/kernel/tsc.c
@@ -459,10 +459,23 @@ static int __init init_tsc_clocksource(v
current_tsc_khz = tsc_khz;
clocksource_tsc.mult = clocksource_khz2mult(current_tsc_khz,
clocksource_tsc.shift);
+#ifndef CONFIG_HIGH_RES_TIMERS
/* lower the rating if we already know its unstable: */
if (check_tsc_unstable())
clocksource_tsc.rating = 0;
-
+#else
+ /*
+ * Mark TSC unsuitable for high resolution timers. 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.
+ */
+ clocksource_tsc.rating = 50;
+ clocksource_tsc.is_continuous = 0;
+#endif
init_timer(&verify_tsc_freq_timer);
verify_tsc_freq_timer.function = verify_tsc_freq;
verify_tsc_freq_timer.expires =
_
Patches currently in -mm which might be from tglx@xxxxxxxxxxxxx are
setup_irq-better-mismatch-debugging.patch
gtod-exponential-update_wall_time.patch
gtod-persistent-clock-support-core.patch
gtod-persistent-clock-support-i386.patch
time-uninline-jiffiesh.patch
time-uninline-jiffiesh-fix.patch
time-fix-msecs_to_jiffies-bug.patch
time-fix-timeout-overflow.patch
cleanup-uninline-irq_enter-and-move-it-into-a-function.patch
dynticks-extend-next_timer_interrupt-to-use-a-reference-jiffie.patch
dynticks-extend-next_timer_interrupt-to-use-a-reference-jiffie-remove-incorrect-warning-in-kernel-timerc.patch
hrtimers-namespace-and-enum-cleanup.patch
hrtimers-clean-up-locking.patch
updated-hrtimers-state-tracking.patch
updated-hrtimers-clean-up-callback-tracking.patch
updated-hrtimers-move-and-add-documentation.patch
updated-add-a-framework-to-manage-clock-event-devices.patch
updated-acpi-include-apich.patch
updated-acpi-keep-track-of-timer-broadcast.patch
updated-acpi-add-state-propagation-for-dynamic-broadcasting.patch
updated-i386-cleanup-apic-code.patch
updated-i386-convert-to-clock-event-devices.patch
updated-pm_timer-allow-early-access-and-move-externs-to-a-header-file.patch
updated-i386-rework-local-apic-calibration.patch
updated-high-res-timers-core.patch
updated-gtod-mark-tsc-unusable-for-highres-timers.patch
updated-dynticks-core-code.patch
updated-dyntick-add-nohz-stats-to-proc-stat.patch
updated-dynticks-i386-arch-code.patch
updated-dynticks-fix-nmi-watchdog.patch
updated-high-res-timers-dynticks-enable-i386-support.patch
updated-debugging-feature-timer-stats.patch
clockevents-core-check-for-clock-event-device-handler-being-non-null-before-calling-it.patch
round_jiffies-infrastructure.patch
round_jiffies-infrastructure-fix.patch
clocksource-add-usage-of-config_sysfs.patch
clocksource-small-cleanup-2.patch
clocksource-small-cleanup-2-fix.patch
clocksource-small-acpi_pm-cleanup.patch
-
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