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| author | Suresh Siddha <suresh.b.siddha@intel.com> | 2011-11-04 15:42:17 -0700 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2011-12-05 18:00:31 +0100 |
| commit | 28a00184be261e3dc152ba0d664a067bbe235b6a (patch) | |
| tree | 9c56ce8c758a244173c9b0016cac43f45609d4ed /arch | |
| parent | 8e8da023f5af71662867729db5547dc54786093c (diff) | |
| download | linux-3.10-28a00184be261e3dc152ba0d664a067bbe235b6a.tar.gz linux-3.10-28a00184be261e3dc152ba0d664a067bbe235b6a.tar.bz2 linux-3.10-28a00184be261e3dc152ba0d664a067bbe235b6a.zip | |
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 <suresh.b.siddha@intel.com>
Acked-by: John Stultz <johnstul@us.ibm.com>
Tested-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/1320446537.15071.14.camel@sbsiddha-desk.sc.intel.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/include/asm/tsc.h | 2 | ||||
| -rw-r--r-- | arch/x86/kernel/tsc.c | 2 | ||||
| -rw-r--r-- | 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 83e2efd181e..15d99153a96 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 db483369f10..eee465109e1 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 0aa5fed8b9e..9eba29b46cb 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; /* |