From 603537719eac6a3391174f10b3b9f0927743d05b Mon Sep 17 00:00:00 2001
From: TellowKrinkle <tellowkrinkle@gmail.com>
Date: Sat, 11 Sep 2021 02:10:06 -0500
Subject: [PATCH] GS: Switch SW renderer statistics back to rdtsc

GetCPUTicks can be pretty low resolution on some systems
---
 common/emitter/cpudetect.cpp              | 15 +++++++++++++++
 common/emitter/tools.h                    |  1 +
 pcsx2/GS/Renderers/Common/GSFunctionMap.h |  8 ++++----
 pcsx2/GS/Renderers/SW/GSRasterizer.cpp    |  4 ++--
 4 files changed, 22 insertions(+), 6 deletions(-)

diff --git a/common/emitter/cpudetect.cpp b/common/emitter/cpudetect.cpp
index 6cdf427c9f..fc47fe0af3 100644
--- a/common/emitter/cpudetect.cpp
+++ b/common/emitter/cpudetect.cpp
@@ -18,6 +18,7 @@
 #include "common/emitter/cpudetect_internal.h"
 #include "common/emitter/internal.h"
 #include "common/emitter/x86_intrin.h"
+#include <atomic>
 
 // CPU information support
 #if defined(_WIN32)
@@ -330,3 +331,17 @@ u32 x86capabilities::CalculateMHz() const
 	else
 		return (u32)(_CPUSpeedHz(span / 500) / 2000);
 }
+
+u32 x86capabilities::CachedMHz()
+{
+	static std::atomic<u32> cached{0};
+	u32 local = cached.load(std::memory_order_relaxed);
+	if (unlikely(local == 0))
+	{
+		x86capabilities caps;
+		caps.Identify();
+		local = caps.CalculateMHz();
+		cached.store(local, std::memory_order_relaxed);
+	}
+	return local;
+}
diff --git a/common/emitter/tools.h b/common/emitter/tools.h
index 93af5c359d..03e07f93f8 100644
--- a/common/emitter/tools.h
+++ b/common/emitter/tools.h
@@ -116,6 +116,7 @@ public:
 	void CountCores();
 	wxString GetTypeName() const;
 
+	static u32 CachedMHz();
 	u32 CalculateMHz() const;
 
 	void SIMD_EstablishMXCSRmask();
diff --git a/pcsx2/GS/Renderers/Common/GSFunctionMap.h b/pcsx2/GS/Renderers/Common/GSFunctionMap.h
index a55009f249..81ba4b936b 100644
--- a/pcsx2/GS/Renderers/Common/GSFunctionMap.h
+++ b/pcsx2/GS/Renderers/Common/GSFunctionMap.h
@@ -19,7 +19,7 @@
 #include "GS/GSCodeBuffer.h"
 
 #include "GS/Renderers/SW/GSScanlineEnvironment.h"
-#include "common/General.h"
+#include "common/emitter/tools.h"
 
 #include <xbyak/xbyak_util.h>
 
@@ -109,9 +109,9 @@ public:
 			totalTicks += p->ticks;
 		}
 
-		double tick_secs = 1.0 / GetTickFrequency();
-		double tick_ms = tick_secs * 1000;
-		double tick_ns = tick_secs * (1000 * 1000 * 1000);
+		double tick_us = 1.0 / x86capabilities::CachedMHz();
+		double tick_ms = tick_us / 1000;
+		double tick_ns = tick_us * 1000;
 
 		printf("GS stats\n");
 
diff --git a/pcsx2/GS/Renderers/SW/GSRasterizer.cpp b/pcsx2/GS/Renderers/SW/GSRasterizer.cpp
index 61deaf053f..7fc7d63040 100644
--- a/pcsx2/GS/Renderers/SW/GSRasterizer.cpp
+++ b/pcsx2/GS/Renderers/SW/GSRasterizer.cpp
@@ -141,7 +141,7 @@ void GSRasterizer::Draw(GSRasterizerData* data)
 	m_pixels.total = 0;
 	m_primcount = 0;
 
-	data->start = GetCPUTicks();
+	data->start = __rdtsc();
 
 	m_ds->BeginDraw(data);
 
@@ -247,7 +247,7 @@ void GSRasterizer::Draw(GSRasterizerData* data)
 
 	data->pixels = m_pixels.actual;
 
-	uint64 ticks = GetCPUTicks() - data->start;
+	uint64 ticks = __rdtsc() - data->start;
 
 	m_pixels.sum += m_pixels.actual;