From 28a00184be261e3dc152ba0d664a067bbe235b6a Mon Sep 17 00:00:00 2001 From: Suresh Siddha Date: Fri, 4 Nov 2011 15:42:17 -0700 Subject: [PATCH] x86, tsc: Skip TSC synchronization checks for tsc=reliable tsc=reliable boot parameter is supposed to skip all the TSC stablility checks during boot time. On a 8-socket system where we want to run an experiment with the "tsc=reliable" boot option, TSC synchronization checks are not getting skipped and marking the TSC as not stable. Check for tsc_clocksource_reliable (which is set via tsc=reliable or for platforms supporting synthetic TSC_RELIABLE feature bit etc) and when set, skip the TSC synchronization tests during boot. Signed-off-by: Suresh Siddha Acked-by: John Stultz Tested-by: Srivatsa S. Bhat Link: http://lkml.kernel.org/r/1320446537.15071.14.camel@sbsiddha-desk.sc.intel.com Signed-off-by: Ingo Molnar --- arch/x86/include/asm/tsc.h | 2 ++ arch/x86/kernel/tsc.c | 2 +- arch/x86/kernel/tsc_sync.c | 4 ++-- 3 files changed, 5 insertions(+), 3 deletions(-) diff --git a/arch/x86/include/asm/tsc.h b/arch/x86/include/asm/tsc.h index 83e2efd181e2..15d99153a96d 100644 --- a/arch/x86/include/asm/tsc.h +++ b/arch/x86/include/asm/tsc.h @@ -51,6 +51,8 @@ extern int unsynchronized_tsc(void); extern int check_tsc_unstable(void); extern unsigned long native_calibrate_tsc(void); +extern int tsc_clocksource_reliable; + /* * Boot-time check whether the TSCs are synchronized across * all CPUs/cores: diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c index db483369f10b..eee465109e16 100644 --- a/arch/x86/kernel/tsc.c +++ b/arch/x86/kernel/tsc.c @@ -35,7 +35,7 @@ static int __read_mostly tsc_unstable; erroneous rdtsc usage on !cpu_has_tsc processors */ static int __read_mostly tsc_disabled = -1; -static int tsc_clocksource_reliable; +int tsc_clocksource_reliable; /* * Scheduler clock - returns current time in nanosec units. */ diff --git a/arch/x86/kernel/tsc_sync.c b/arch/x86/kernel/tsc_sync.c index 0aa5fed8b9e6..9eba29b46cb7 100644 --- a/arch/x86/kernel/tsc_sync.c +++ b/arch/x86/kernel/tsc_sync.c @@ -113,7 +113,7 @@ void __cpuinit check_tsc_sync_source(int cpu) if (unsynchronized_tsc()) return; - if (boot_cpu_has(X86_FEATURE_TSC_RELIABLE)) { + if (tsc_clocksource_reliable) { if (cpu == (nr_cpu_ids-1) || system_state != SYSTEM_BOOTING) pr_info( "Skipped synchronization checks as TSC is reliable.\n"); @@ -172,7 +172,7 @@ void __cpuinit check_tsc_sync_target(void) { int cpus = 2; - if (unsynchronized_tsc() || boot_cpu_has(X86_FEATURE_TSC_RELIABLE)) + if (unsynchronized_tsc() || tsc_clocksource_reliable) return; /* -- 2.34.1