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authorThomas Gleixner <tglx@linutronix.de>2023-02-13 19:28:48 +0100
committerThomas Gleixner <tglx@linutronix.de>2023-02-13 19:28:48 +0100
commitab407a1919d2676ddc5761ed459d4cc5c7be18ed (patch)
tree6597d7b8809116e246350bc80e77051477b9a769 /drivers/clocksource
parent7b0f95f28fc74f2a92662c26044d9d31c5ffd1e1 (diff)
parent0051293c533017e2a860e0a0a33517bc40240fff (diff)
Merge tag 'clocksource.2023.02.06b' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into timers/core
Pull clocksource watchdog changes from Paul McKenney: o Improvements to clocksource-watchdog console messages. o Loosening of the clocksource-watchdog skew criteria to match those of NTP (500 parts per million, relaxed from 400 parts per million). If it is good enough for NTP, it is good enough for the clocksource watchdog. o Suspend clocksource-watchdog checking temporarily when high memory latencies are detected. This avoids the false-positive clock-skew events that have been seen on production systems running memory-intensive workloads. o On systems where the TSC is deemed trustworthy, use it as the watchdog timesource, but only when specifically requested using the tsc=watchdog kernel boot parameter. This permits clock-skew events to be detected, but avoids forcing workloads to use the slow HPET and ACPI PM timers. These last two timers are slow enough to cause systems to be needlessly marked bad on the one hand, and real skew does sometimes happen on production systems running production workloads on the other. And sometimes it is the fault of the TSC, or at least of the firmware that told the kernel to program the TSC with the wrong frequency. o Add a tsc=revalidate kernel boot parameter to allow the kernel to diagnose cases where the TSC hardware works fine, but was told by firmware to tick at the wrong frequency. Such cases are rare, but they really have happened on production systems. Link: https://lore.kernel.org/r/20230210193640.GA3325193@paulmck-ThinkPad-P17-Gen-1
Diffstat (limited to 'drivers/clocksource')
-rw-r--r--drivers/clocksource/acpi_pm.c6
1 files changed, 4 insertions, 2 deletions
diff --git a/drivers/clocksource/acpi_pm.c b/drivers/clocksource/acpi_pm.c
index 279ddff81ab4..82338773602c 100644
--- a/drivers/clocksource/acpi_pm.c
+++ b/drivers/clocksource/acpi_pm.c
@@ -23,6 +23,7 @@
#include <linux/pci.h>
#include <linux/delay.h>
#include <asm/io.h>
+#include <asm/time.h>
/*
* The I/O port the PMTMR resides at.
@@ -210,8 +211,9 @@ static int __init init_acpi_pm_clocksource(void)
return -ENODEV;
}
- return clocksource_register_hz(&clocksource_acpi_pm,
- PMTMR_TICKS_PER_SEC);
+ if (tsc_clocksource_watchdog_disabled())
+ clocksource_acpi_pm.flags |= CLOCK_SOURCE_MUST_VERIFY;
+ return clocksource_register_hz(&clocksource_acpi_pm, PMTMR_TICKS_PER_SEC);
}
/* We use fs_initcall because we want the PCI fixups to have run