From 48efdb18daecf0164bd2ca5f35ff157596e6d393 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Branimir=20Karad=C5=BEi=C4=87?= <branimirkaradzic@gmail.com>
Date: Mon, 22 Jun 2026 00:28:50 -0700
Subject: [PATCH] Metal: Implement timer queries. Closes #3774. (#3778)

---
 src/renderer_mtl.cpp | 39 ++++++++++++++++++++++-----------------
 src/renderer_mtl.h   |  2 +-
 2 files changed, 23 insertions(+), 18 deletions(-)

diff --git a/src/renderer_mtl.cpp b/src/renderer_mtl.cpp
index 2bb32d48b..3202a28ee 100644
--- a/src/renderer_mtl.cpp
+++ b/src/renderer_mtl.cpp
@@ -4613,9 +4613,16 @@ static_assert(BX_COUNTOF(s_accessNames) == Access::Count, "Invalid s_accessNames
 		ra.clear();
 	}
 
+	static constexpr uint64_t kNanosecondsPerSecond = UINT64_C(1000000000);
+
 	void TimerQueryMtl::init()
 	{
-		m_frequency = bx::getHPFrequency();
+		m_frequency = kNanosecondsPerSecond;
+
+		for (uint32_t ii = 0; ii < BX_COUNTOF(m_result); ++ii)
+		{
+			m_result[ii].reset();
+		}
 	}
 
 	void TimerQueryMtl::shutdown()
@@ -4624,8 +4631,7 @@ static_assert(BX_COUNTOF(s_accessNames) == Access::Count, "Invalid s_accessNames
 
 	uint32_t TimerQueryMtl::begin(uint32_t _resultIdx, uint32_t _frameNum)
 	{
-		BX_UNUSED(_resultIdx);
-		BX_UNUSED(_frameNum);
+		BX_UNUSED(_resultIdx, _frameNum);
 		return 0;
 	}
 
@@ -4634,11 +4640,6 @@ static_assert(BX_COUNTOF(s_accessNames) == Access::Count, "Invalid s_accessNames
 		BX_UNUSED(_idx);
 	}
 
-	static void setTimestamp(void* _data)
-	{
-		*( (int64_t*)_data) = bx::getHPCounter();
-	}
-
 	void TimerQueryMtl::addHandlers(MTL::CommandBuffer*& _commandBuffer)
 	{
 		while (0 == m_control.reserve(1) )
@@ -4646,14 +4647,18 @@ static_assert(BX_COUNTOF(s_accessNames) == Access::Count, "Invalid s_accessNames
 			m_control.consume(1);
 		}
 
-		uint32_t offset = m_control.m_current;
+		const uint32_t offset = m_control.m_current;
 
-		_commandBuffer->addScheduledHandler(
-			MTL::HandlerFunction([pBegin = &m_result[offset].m_begin](MTL::CommandBuffer*) { setTimestamp(pBegin); })
-			);
 		_commandBuffer->addCompletedHandler(
-			MTL::HandlerFunction([pEnd = &m_result[offset].m_end](MTL::CommandBuffer*) { setTimestamp(pEnd); })
+			MTL::HandlerFunction([this, offset](MTL::CommandBuffer* _cmdBuf)
+			{
+				const double gpuBegin = _cmdBuf->GPUStartTime();
+				const double gpuEnd   = _cmdBuf->GPUEndTime();
+				m_result[offset].m_begin = uint64_t(gpuBegin * double(kNanosecondsPerSecond) );
+				m_result[offset].m_end   = uint64_t(gpuEnd   * double(kNanosecondsPerSecond) );
+			})
 			);
+
 		m_control.commit(1);
 	}
 
@@ -4662,8 +4667,8 @@ static_assert(BX_COUNTOF(s_accessNames) == Access::Count, "Invalid s_accessNames
 		if (0 != m_control.getNumUsed() )
 		{
 			uint32_t offset = m_control.m_read;
-			m_begin = m_result[offset].m_begin;
-			m_end   = m_result[offset].m_end;
+			m_begin   = m_result[offset].m_begin;
+			m_end     = m_result[offset].m_end;
 			m_elapsed = m_end - m_begin;
 
 			m_control.consume(1);
@@ -4849,8 +4854,6 @@ static_assert(BX_COUNTOF(s_accessNames) == Access::Count, "Invalid s_accessNames
 		int64_t timeBegin = bx::getHPCounter();
 		int64_t captureElapsed = 0;
 
-		m_gpuTimer.addHandlers(m_commandBuffer);
-
 		if (m_blitCommandEncoder)
 		{
 			m_blitCommandEncoder->endEncoding();
@@ -6123,6 +6126,8 @@ static_assert(BX_COUNTOF(s_accessNames) == Access::Count, "Invalid s_accessNames
 
 		if (NULL != m_commandBuffer)
 		{
+			m_gpuTimer.addHandlers(m_commandBuffer);
+
 			m_cmd.kick(true, false);
 			m_commandBuffer = NULL;
 		}
diff --git a/src/renderer_mtl.h b/src/renderer_mtl.h
index d9c003117..a8a3010ac 100644
--- a/src/renderer_mtl.h
+++ b/src/renderer_mtl.h
@@ -626,7 +626,7 @@ namespace bgfx { namespace mtl
 			uint64_t m_begin;
 			uint64_t m_end;
 			uint32_t m_pending;
-			uint32_t m_frameNum; // TODO: implement (currently stays 0)
+			uint32_t m_frameNum;
 		};
 
 		uint64_t m_begin;