From e7a543b77f9c03a171db8e8e13c8fd88c270720a Mon Sep 17 00:00:00 2001
From: Georgy Stolbovoy <georgystolbovoy2000@gmail.com>
Date: Fri, 12 Jun 2026 17:27:22 +0300
Subject: [PATCH] fix time measurement when EASY_CHRONO_CLOCK is defined

---
 easy_profiler_core/event_trace_win.cpp | 27 ++++++++++++++++++++++++++
 easy_profiler_core/profile_manager.cpp | 10 +++++++---
 2 files changed, 34 insertions(+), 3 deletions(-)

diff --git a/easy_profiler_core/event_trace_win.cpp b/easy_profiler_core/event_trace_win.cpp
index bdb4d7b1..01a6b81d 100644
--- a/easy_profiler_core/event_trace_win.cpp
+++ b/easy_profiler_core/event_trace_win.cpp
@@ -209,6 +209,26 @@ static thread_process_info_map THREAD_PROCESS_INFO_TABLE;
 
 //////////////////////////////////////////////////////////////////////////
 
+// "The frequency of the performance counter is fixed at system boot and is consistent across all processors.
+// Therefore, the frequency need only be queried upon application initialization, and the result can be cached."
+// © https://learn.microsoft.com/en-us/windows/win32/api/profileapi/nf-profileapi-queryperformancefrequency
+extern const LONGLONG PERFORMANCE_FREQUENCY = []()
+{
+    LARGE_INTEGER freq;
+    QueryPerformanceFrequency(&freq);
+    return freq.QuadPart;
+}();
+
+#ifdef EASY_CHRONO_CLOCK
+static profiler::timestamp_t ticks2time(LONGLONG ticks)
+{
+    EASY_CONSTEXPR auto clock_freq = EASY_CHRONO_CLOCK::period::den / EASY_CHRONO_CLOCK::period::num;
+    return static_cast<profiler::timestamp_t>(static_cast<double>(ticks) / PERFORMANCE_FREQUENCY * clock_freq);
+}
+#endif
+
+//////////////////////////////////////////////////////////////////////////
+
 void WINAPI easyProcessTraceEvent(PEVENT_RECORD _traceEvent)
 {
     if (_traceEvent->EventHeader.EventDescriptor.Opcode != SWITCH_CONTEXT_OPCODE)
@@ -220,7 +240,14 @@ void WINAPI easyProcessTraceEvent(PEVENT_RECORD _traceEvent)
     EASY_FUNCTION(EASY_COLOR_INTERNAL_EVENT, profiler::OFF);
 
     auto _contextSwitchEvent = reinterpret_cast<CSwitch*>(_traceEvent->UserData);
+
+#ifdef EASY_CHRONO_CLOCK
+    // We need to use uniform time units, so we need to cast the ticks to time of the clock.
+    const auto time = ticks2time(_traceEvent->EventHeader.TimeStamp.QuadPart);
+#else
+    // OK, time is measured only in ticks.
     const auto time = static_cast<profiler::timestamp_t>(_traceEvent->EventHeader.TimeStamp.QuadPart);
+#endif
     if (time > TRACING_END_TIME.load(std::memory_order_acquire))
         return;
 
diff --git a/easy_profiler_core/profile_manager.cpp b/easy_profiler_core/profile_manager.cpp
index 12fe96d8..f8df9e4c 100644
--- a/easy_profiler_core/profile_manager.cpp
+++ b/easy_profiler_core/profile_manager.cpp
@@ -152,6 +152,12 @@ EASY_CONSTEXPR profiler::color_t EASY_COLOR_END = 0xfff44336; // profiler::color
 
 //////////////////////////////////////////////////////////////////////////
 
+#ifdef _WIN32
+extern const LONGLONG PERFORMANCE_FREQUENCY;
+#endif
+
+//////////////////////////////////////////////////////////////////////////
+
 EASY_CONSTEXPR uint8_t FORCE_ON_FLAG = profiler::FORCE_ON & ~profiler::ON;
 
 //////////////////////////////////////////////////////////////////////////
@@ -259,9 +265,7 @@ static EASY_CONSTEXPR_FCN int64_t calculate_cpu_frequency()
 #elif defined(_WIN32)
 static int64_t calculate_cpu_frequency()
 {
-    LARGE_INTEGER freq;
-    QueryPerformanceFrequency(&freq);
-    return static_cast<int64_t>(freq.QuadPart);
+    return static_cast<int64_t>(PERFORMANCE_FREQUENCY);
 }
 #else
 # ifndef __APPLE__