summaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
authorSuresh Siddha <suresh.b.siddha@intel.com>2011-11-04 15:42:17 -0700
committerIngo Molnar <mingo@elte.hu>2011-12-05 18:00:31 +0100
commit28a00184be261e3dc152ba0d664a067bbe235b6a (patch)
tree9c56ce8c758a244173c9b0016cac43f45609d4ed
parent8e8da023f5af71662867729db5547dc54786093c (diff)
downloadop-kernel-dev-28a00184be261e3dc152ba0d664a067bbe235b6a.zip
op-kernel-dev-28a00184be261e3dc152ba0d664a067bbe235b6a.tar.gz
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>
-rw-r--r--arch/x86/include/asm/tsc.h2
-rw-r--r--arch/x86/kernel/tsc.c2
-rw-r--r--arch/x86/kernel/tsc_sync.c4
3 files changed, 5 insertions, 3 deletions
diff --git a/arch/x86/include/asm/tsc.h b/arch/x86/include/asm/tsc.h
index 83e2efd..15d9915 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 db48336..eee4651 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 0aa5fed8..9eba29b 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;
/*
OpenPOWER on IntegriCloud