From 6bd4345bf5c749f19b0742cc8dc60b298619c9b3 Mon Sep 17 00:00:00 2001
From: Leonid Evdokimov <leon@darkk.net.ru>
Date: Thu, 11 Jul 2024 09:41:22 +0300
Subject: [PATCH] Warn on lack of CPU cycle counter

---
 Platform.h    | 6 ++++++
 SpeedTest.cpp | 5 +++++
 2 files changed, 11 insertions(+)

diff --git a/Platform.h b/Platform.h
index 0924c184..609fed64 100644
--- a/Platform.h
+++ b/Platform.h
@@ -57,6 +57,7 @@ void SetAffinity ( int cpu );
 
 #pragma intrinsic(__rdtsc)
 // Read Time Stamp Counter
+#define timer_counts_ns() (false)
 #define rdtsc()       __rdtsc()
 #define timer_start() __rdtsc()
 #define timer_end()   __rdtsc()
@@ -251,6 +252,11 @@ __inline__ uint64_t timer_end()
 #endif
 }
 
+__inline__ bool timer_counts_ns ( void )
+{
+  const double ratio = double(timer_start()) / timeofday();
+  return (0.999 < ratio && ratio < 1.001);
+}
 
 #include <strings.h>
 #define _stricmp strcasecmp
diff --git a/SpeedTest.cpp b/SpeedTest.cpp
index 0f4efa6c..23db9c46 100644
--- a/SpeedTest.cpp
+++ b/SpeedTest.cpp
@@ -273,6 +273,11 @@ void BulkSpeedTest ( pfHash hash, uint32_t seed )
   const int trials = 2999;
   const int blocksize = 256 * 1024;
 
+  if (timer_counts_ns())
+    printf("WARNING: no cycle counter, cycle == 1ns\n");
+  if (timer_start() == timer_end())
+    printf("WARNING: timer resolution is low\n");
+
   printf("Bulk speed test - %d-byte keys\n",blocksize);
   double sumbpc = 0.0;