Merge pull request #7809 from Morph1984/clock-constants

common: wall_clock: Utilize constants for ms, us, and ns ratios

1 files changed, 10 insertions, 6 deletions

diff --git a/src/common/wall_clock.cpp b/src/common/wall_clock.cpp
index ffa282e888..9acf7551ef 100644
--- a/src/common/wall_clock.cpp
+++ b/src/common/wall_clock.cpp
@@ -65,16 +65,20 @@ private:
 
 #ifdef ARCHITECTURE_x86_64
 
-std::unique_ptr<WallClock> CreateBestMatchingClock(u32 emulated_cpu_frequency,
-                                                   u32 emulated_clock_frequency) {
+std::unique_ptr<WallClock> CreateBestMatchingClock(u64 emulated_cpu_frequency,
+                                                   u64 emulated_clock_frequency) {
     const auto& caps = GetCPUCaps();
     u64 rtsc_frequency = 0;
     if (caps.invariant_tsc) {
         rtsc_frequency = EstimateRDTSCFrequency();
     }
 
-    // Fallback to StandardWallClock if rtsc period is higher than a nano second
-    if (rtsc_frequency <= 1000000000) {
+    // Fallback to StandardWallClock if the hardware TSC does not have the precision greater than:
+    // - A nanosecond
+    // - The emulated CPU frequency
+    // - The emulated clock counter frequency (CNTFRQ)
+    if (rtsc_frequency <= WallClock::NS_RATIO || rtsc_frequency <= emulated_cpu_frequency ||
+        rtsc_frequency <= emulated_clock_frequency) {
         return std::make_unique<StandardWallClock>(emulated_cpu_frequency,
                                                    emulated_clock_frequency);
     } else {
@@ -85,8 +89,8 @@ std::unique_ptr<WallClock> CreateBestMatchingClock(u32 emulated_cpu_frequency,
 
 #else
 
-std::unique_ptr<WallClock> CreateBestMatchingClock(u32 emulated_cpu_frequency,
-                                                   u32 emulated_clock_frequency) {
+std::unique_ptr<WallClock> CreateBestMatchingClock(u64 emulated_cpu_frequency,
+                                                   u64 emulated_clock_frequency) {
     return std::make_unique<StandardWallClock>(emulated_cpu_frequency, emulated_clock_frequency);
 }