summaryrefslogtreecommitdiff
path: root/arch/i386/kernel/tsc.c
diff options
context:
space:
mode:
authorJustin Waters <justin.waters@timesys.com>2008-02-26 13:07:02 -0500
committerJustin Waters <justin.waters@timesys.com>2008-02-26 13:07:02 -0500
commitb80a32b9cc634adfa8eaef33ec981e7febf2ade2 (patch)
treef256bce13ba11f514a388160df84e1410bedbe2b /arch/i386/kernel/tsc.c
parent594133ef22fae0d737bd1b57352cf3f48a192c63 (diff)
Update the i.MX31 Kernel to 2.6.232.6.23-mx31ads-2008022618072.6.23-mx31-200802261807
This is the result of a brute-force attempt to update the kernel to 2.6.23. Now that we have a git tree, our effort will be a little nicer in the future. Signed-off-by: Justin Waters <justin.waters@timesys.com>
Diffstat (limited to 'arch/i386/kernel/tsc.c')
-rw-r--r--arch/i386/kernel/tsc.c35
1 files changed, 25 insertions, 10 deletions
diff --git a/arch/i386/kernel/tsc.c b/arch/i386/kernel/tsc.c
index f64b81f3033b..a39280b4dd3a 100644
--- a/arch/i386/kernel/tsc.c
+++ b/arch/i386/kernel/tsc.c
@@ -4,6 +4,7 @@
* See comments there for proper credits.
*/
+#include <linux/sched.h>
#include <linux/clocksource.h>
#include <linux/workqueue.h>
#include <linux/cpufreq.h>
@@ -26,6 +27,7 @@ static int tsc_enabled;
* an extra value to store the TSC freq
*/
unsigned int tsc_khz;
+EXPORT_SYMBOL_GPL(tsc_khz);
int tsc_disable;
@@ -57,10 +59,11 @@ __setup("notsc", tsc_setup);
*/
static int tsc_unstable;
-static inline int check_tsc_unstable(void)
+int check_tsc_unstable(void)
{
return tsc_unstable;
}
+EXPORT_SYMBOL_GPL(check_tsc_unstable);
/* Accellerators for sched_clock()
* convert from cycles(64bits) => nanoseconds (64bits)
@@ -83,7 +86,7 @@ static inline int check_tsc_unstable(void)
*
* -johnstul@us.ibm.com "math is hard, lets go shopping!"
*/
-static unsigned long cyc2ns_scale __read_mostly;
+unsigned long cyc2ns_scale __read_mostly;
#define CYC2NS_SCALE_FACTOR 10 /* 2^10, carefully chosen */
@@ -92,32 +95,44 @@ static inline void set_cyc2ns_scale(unsigned long cpu_khz)
cyc2ns_scale = (1000000 << CYC2NS_SCALE_FACTOR)/cpu_khz;
}
-static inline unsigned long long cycles_2_ns(unsigned long long cyc)
-{
- return (cyc * cyc2ns_scale) >> CYC2NS_SCALE_FACTOR;
-}
-
/*
* Scheduler clock - returns current time in nanosec units.
*/
-unsigned long long sched_clock(void)
+unsigned long long native_sched_clock(void)
{
unsigned long long this_offset;
/*
* Fall back to jiffies if there's no TSC available:
+ * ( But note that we still use it if the TSC is marked
+ * unstable. We do this because unlike Time Of Day,
+ * the scheduler clock tolerates small errors and it's
+ * very important for it to be as fast as the platform
+ * can achive it. )
*/
- if (unlikely(!tsc_enabled))
+ if (unlikely(!tsc_enabled && !tsc_unstable))
/* No locking but a rare wrong value is not a big deal: */
return (jiffies_64 - INITIAL_JIFFIES) * (1000000000 / HZ);
/* read the Time Stamp Counter: */
- get_scheduled_cycles(this_offset);
+ rdtscll(this_offset);
/* return the value in ns */
return cycles_2_ns(this_offset);
}
+/* We need to define a real function for sched_clock, to override the
+ weak default version */
+#ifdef CONFIG_PARAVIRT
+unsigned long long sched_clock(void)
+{
+ return paravirt_sched_clock();
+}
+#else
+unsigned long long sched_clock(void)
+ __attribute__((alias("native_sched_clock")));
+#endif
+
unsigned long native_calculate_cpu_khz(void)
{
unsigned long long start, end;