[PATCH 3/3] oslat: Allow for arch specific timer frequency measurements

[Nicolas Saenz Julienne <nsaenzju@redhat.com>]

Some architectures have special purpose registers to query the system
timer's frequency. Let's use that when available.

Signed-off-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>
---
 src/oslat/oslat.c | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/src/oslat/oslat.c b/src/oslat/oslat.c
index bd155a6..23ca9b6 100644
--- a/src/oslat/oslat.c
+++ b/src/oslat/oslat.c
@@ -51,6 +51,9 @@
 # define atomic_inc(ptr)   __sync_add_and_fetch((ptr), 1)
 # if defined(__x86_64__)
 #  define relax()          __asm__ __volatile__("pause" ::: "memory")
+
+#define measure_timer_mhz generic_measure_timer_mhz
+
 static inline void frc(uint64_t *pval)
 {
 	uint32_t low, high;
@@ -61,12 +64,18 @@ static inline void frc(uint64_t *pval)
 }
 # elif defined(__i386__)
 #  define relax()          __asm__ __volatile__("pause" ::: "memory")
+
+#define measure_timer_mhz generic_measure_timer_mhz
+
 static inline void frc(uint64_t *pval)
 {
 	__asm__ __volatile__("rdtsc" : "=A" (*pval));
 }
 # elif defined(__PPC64__)
 #  define relax()          do { } while (0)
+
+#define measure_timer_mhz generic_measure_timer_mhz
+
 static inline void frc(uint64_t *pval)
 {
 	__asm__ __volatile__("mfspr %0, 268\n" : "=r" (*pval));
@@ -74,6 +83,15 @@ static inline void frc(uint64_t *pval)
 # elif defined(__aarch64__)
 #  define relax()          __asm__ __volatile("yield" : : : "memory")
 
+static inline unsigned int measure_timer_mhz(void)
+{
+	unsigned int val;
+
+	__asm__ __volatile__("mrs %0, cntfrq_el0" : "=r" (val));
+
+	return val / 1e6;
+}
+
 static inline void frc(uint64_t *pval)
 {
 
@@ -257,7 +275,7 @@ static cycles_t __measure_timer_hz(void)
 	return (cycles_t) ((e - s) / sec);
 }
 
-static unsigned int measure_timer_mhz(void)
+static unsigned int __attribute__((unused)) generic_measure_timer_mhz(void)
 {
 	cycles_t m, mprev, d;
 
-- 
2.31.1