diff options
| -rw-r--r-- | Documentation/kernel-parameters.txt | 9 | ||||
| -rw-r--r-- | arch/x86/kernel/tsc.c | 7 |
2 files changed, 10 insertions, 6 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 92e83e53148f..c7c8eca5b2b3 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -2467,12 +2467,13 @@ and is between 256 and 4096 characters. It is defined in the file to facilitate early boot debugging. See also Documentation/trace/events.txt - tsc= Disable clocksource-must-verify flag for TSC. + tsc= Disable clocksource stability checks for TSC. Format: <string> [x86] reliable: mark tsc clocksource as reliable, this - disables clocksource verification at runtime. - Used to enable high-resolution timer mode on older - hardware, and in virtualized environment. + disables clocksource verification at runtime, as well + as the stability checks done at bootup. Used to enable + high-resolution timer mode on older hardware, and in + virtualized environment. [x86] noirqtime: Do not use TSC to do irq accounting. Used to run time disable IRQ_TIME_ACCOUNTING on any platforms where RDTSC is slow and this accounting diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c index 0c40d8b72416..bb64beb301d9 100644 --- a/arch/x86/kernel/tsc.c +++ b/arch/x86/kernel/tsc.c @@ -872,6 +872,9 @@ __cpuinit int unsynchronized_tsc(void) if (boot_cpu_has(X86_FEATURE_CONSTANT_TSC)) return 0; + + if (tsc_clocksource_reliable) + return 0; /* * Intel systems are normally all synchronized. * Exceptions must mark TSC as unstable: @@ -879,10 +882,10 @@ __cpuinit int unsynchronized_tsc(void) if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL) { /* assume multi socket systems are not synchronized: */ if (num_possible_cpus() > 1) - tsc_unstable = 1; + return 1; } - return tsc_unstable; + return 0; } static void __init init_tsc_clocksource(void) |