UbiquitousOS
/
OpenCloudOS-Kernel
mirror of https://gitee.com/OpenCloudOS/OpenCloudOS-Kernel.git
11
0
Fork 0
Code Issues Projects Releases Wiki Activity

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>
This commit is contained in:
Paul E. McKenney 2023-02-01 13:53:07 -08:00
parent efc8b329c7
commit 0051293c53
2 changed files with 22 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
Documentation/admin-guide/kernel-parameters.txt
View File

@ -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

18
arch/x86/kernel/tsc.c
View File

@ -294,6 +294,7 @@ __setup("notsc", notsc_setup);
static int no_sched_irq_time;
static int no_tsc_watchdog;
static int tsc_as_watchdog;
static int __init tsc_setup(char *str)
{
@ -303,10 +304,22 @@ static int __init tsc_setup(char *str)
no_sched_irq_time = 1;
if (!strcmp(str, "unstable"))
mark_tsc_unstable("boot parameter");
if (!strcmp(str, "nowatchdog"))
if (!strcmp(str, "nowatchdog")) {
no_tsc_watchdog = 1;
if (tsc_as_watchdog)
pr_alert("%s: Overriding earlier tsc=watchdog with tsc=nowatchdog\n",
__func__);
tsc_as_watchdog = 0;
}
if (!strcmp(str, "recalibrate"))
tsc_force_recalibrate = 1;
if (!strcmp(str, "watchdog")) {
if (no_tsc_watchdog)
pr_alert("%s: tsc=watchdog overridden by earlier tsc=nowatchdog\n",
__func__);
else
tsc_as_watchdog = 1;
}
return 1;
}
@ -1192,7 +1205,8 @@ static void __init tsc_disable_clocksource_watchdog(void)
bool tsc_clocksource_watchdog_disabled(void)
{
return !(clocksource_tsc.flags & CLOCK_SOURCE_MUST_VERIFY);
return !(clocksource_tsc.flags & CLOCK_SOURCE_MUST_VERIFY) &&
tsc_as_watchdog && !no_tsc_watchdog;
}
static void __init check_system_tsc_reliable(void)