From 0f0b7e1cc7abf8e1a8b301f2868379d611d05ae2 Mon Sep 17 00:00:00 2001 From: Juri Lelli Date: Thu, 7 Mar 2019 13:09:13 +0100 Subject: x86/tsc: Add option to disable tsc clocksource watchdog Clocksource watchdog has been found responsible for generating latency spikes (in the 10-20 us range) when woken up to check for TSC stability. Add an option to disable it at boot. Signed-off-by: Juri Lelli Signed-off-by: Thomas Gleixner Cc: bigeasy@linutronix.de Cc: linux-rt-users@vger.kernel.org Cc: peterz@infradead.org Cc: bristot@redhat.com Cc: williams@redhat.com Link: https://lkml.kernel.org/r/20190307120913.13168-1-juri.lelli@redhat.com --- arch/x86/kernel/tsc.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'arch/x86/kernel/tsc.c') diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c index 3fae23834069..aab0c82e0a0d 100644 --- a/arch/x86/kernel/tsc.c +++ b/arch/x86/kernel/tsc.c @@ -283,6 +283,7 @@ int __init notsc_setup(char *str) __setup("notsc", notsc_setup); static int no_sched_irq_time; +static int no_tsc_watchdog; static int __init tsc_setup(char *str) { @@ -292,6 +293,8 @@ 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")) + no_tsc_watchdog = 1; return 1; } @@ -1349,7 +1352,7 @@ static int __init init_tsc_clocksource(void) if (tsc_unstable) goto unreg; - if (tsc_clocksource_reliable) + if (tsc_clocksource_reliable || no_tsc_watchdog) clocksource_tsc.flags &= ~CLOCK_SOURCE_MUST_VERIFY; if (boot_cpu_has(X86_FEATURE_NONSTOP_TSC_S3)) -- cgit v1.2.3