api: cpu: added cpu cycle count API

Raw CPU cycle counts can be used to measure performance
in CPU cycles. These functions will replace some usage of
odp_time_cycles() of odp_time_diff_cycles().

Signed-off-by: Petri Savolainen <petri.savolainen@nokia.com>
Reviewed-by: Ivan Khoronzhuk <ivan.khoronzhuk@linaro.org>
Signed-off-by: Maxim Uvarov <maxim.uvarov@linaro.org>

1 files changed, 52 insertions, 0 deletions

diff --git a/include/odp/api/cpu.h b/include/odp/api/cpu.h
index c38909321..50a7e3da5 100644
--- a/include/odp/api/cpu.h
+++ b/include/odp/api/cpu.h
@@ -18,6 +18,8 @@
 extern "C" {
 #endif
 
+#include <odp/std_types.h>
+
 /** @defgroup odp_cpu ODP CPU
  *  @{
  */
@@ -44,6 +46,56 @@ int odp_cpu_id(void);
 int odp_cpu_count(void);
 
 /**
+ * Current CPU cycle count
+ *
+ * Return current CPU cycle count. Cycle count may not be reset at ODP init
+ * and thus may wrap back to zero between two calls. Use odp_cpu_cycles_max()
+ * to read the maximum count value after which it wraps. Cycle count frequency
+ * follows the CPU frequency and thus may change at any time. The count may
+ * advance in steps larger than one. Use odp_cpu_cycles_resolution() to read
+ * the step size.
+ *
+ * @note Do not use CPU count for time measurements since the frequency may
+ * vary.
+ *
+ * @return Current CPU cycle count
+ */
+uint64_t odp_cpu_cycles(void);
+
+/**
+ * CPU cycle count difference
+ *
+ * Calculate difference between cycle counts c1 and c2. Parameter c1 must be the
+ * first cycle count sample and c2 the second. The function handles correctly
+ * single cycle count wrap between c1 and c2.
+ *
+ * @param c1    First cycle count
+ * @param c2    Second cycle count
+ *
+ * @return CPU cycles from c1 to c2
+ */
+uint64_t odp_cpu_cycles_diff(uint64_t c1, uint64_t c2);
+
+/**
+ * Maximum CPU cycle count
+ *
+ * Maximum CPU cycle count value before it wraps back to zero.
+ *
+ * @return Maximum CPU cycle count value
+ */
+uint64_t odp_cpu_cycles_max(void);
+
+/**
+ * Resolution of CPU cycle count
+ *
+ * CPU cycle count may advance in steps larger than one. This function returns
+ * resolution of odp_cpu_cycles() in CPU cycles.
+ *
+ * @return CPU cycle count resolution in CPU cycles
+ */
+uint64_t odp_cpu_cycles_resolution(void);
+
+/**
  * @}
  */