The following commit has been merged into the timers/core branch of tip:
Commit-ID: ab407a1919d2676ddc5761ed459d4cc5c7be18ed
Gitweb: https://git.kernel.org/tip/ab407a1919d2676ddc5761ed459d4cc5c7be18ed
Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
AuthorDate: Mon, 13 Feb 2023 19:28:48 +01:00
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitterDate: Mon, 13 Feb 2023 19:28:48 +01:00
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
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