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authorPaul E. McKenney <paulmck@kernel.org>2023-02-01 13:53:07 -0800
committerPaul E. McKenney <paulmck@kernel.org>2023-02-06 16:38:30 -0800
commit0051293c533017e2a860e0a0a33517bc40240fff (patch)
tree54297a31350169661fd6f40446cf5f49025dd9bd /Documentation/admin-guide/kernel-parameters.txt
parentefc8b329c7fdc30921a7dfc109237523e1e5b1cc (diff)
clocksource: Enable TSC watchdog checking of HPET and PMTMR only when requested
Unconditionally enabling TSC watchdog checking of the HPET and PMTMR clocksources can degrade latency and performance. Therefore, provide a new "watchdog" option to the tsc= boot parameter that opts into such checking. Note that tsc=watchdog is overridden by a tsc=nowatchdog regardless of their relative positions in the list of boot parameters. Reported-by: Thomas Gleixner <tglx@linutronix.de> Reported-by: Waiman Long <longman@redhat.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Acked-by: Waiman Long <longman@redhat.com>
Diffstat (limited to 'Documentation/admin-guide/kernel-parameters.txt')
-rw-r--r--Documentation/admin-guide/kernel-parameters.txt6
1 files changed, 6 insertions, 0 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 95f0d104c232..7b4df6d89d3c 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -6373,6 +6373,12 @@
(HPET or PM timer) on systems whose TSC frequency was
obtained from HW or FW using either an MSR or CPUID(0x15).
Warn if the difference is more than 500 ppm.
+ [x86] watchdog: Use TSC as the watchdog clocksource with
+ which to check other HW timers (HPET or PM timer), but
+ only on systems where TSC has been deemed trustworthy.
+ This will be suppressed by an earlier tsc=nowatchdog and
+ can be overridden by a later tsc=nowatchdog. A console
+ message will flag any such suppression or overriding.
tsc_early_khz= [X86] Skip early TSC calibration and use the given
value instead. Useful when the early TSC frequency discovery