Arm system counter cleanup

[vpp.git] / src / vppinfra / time.c

diff --git a/src/vppinfra/time.c b/src/vppinfra/time.c
index 770ed8b..1626ff4 100644 (file)
--- a/src/vppinfra/time.c
+++ b/src/vppinfra/time.c
@@ -142,17 +142,20 @@ done:
 f64
 os_cpu_clock_frequency (void)
 {
+#if defined (__aarch64__)
+  /* The system counter increments at a fixed frequency. It is distributed
+   * to each core which has registers for reading the current counter value
+   * as well as the clock frequency. The system counter is not clocked at
+   * the same frequency as the core. */
+  u32 hz;
+  asm volatile ("mrs %0, cntfrq_el0":"=r" (hz));
+  return (f64) hz;
+#endif
   f64 cpu_freq;
 
   if (clib_cpu_supports_invariant_tsc ())
     return estimate_clock_frequency (1e-3);
 
-#if defined (__aarch64__)
-  u64 tsc;
-  asm volatile ("mrs %0, CNTFRQ_EL0":"=r" (tsc));
-  return (f64) tsc;
-#endif
-
   /* First try /sys version. */
   cpu_freq = clock_frequency_from_sys_filesystem ();
   if (cpu_freq != 0)