multithread the MD5/IQM model CPU code using OpenMP

CMakeLists.txt

@@ -827,7 +827,8 @@ macro(AddApplicationInternal Target Executable)
         add_dependencies(${Target} runtime_deps)
     endif()
 
-    set_property(TARGET ${Target} APPEND PROPERTY COMPILE_OPTIONS ${A_Flags})
+    set_property(TARGET ${Target} APPEND PROPERTY COMPILE_OPTIONS ${A_CompileFlags})
+    set_property(TARGET ${Target} APPEND PROPERTY LINK_OPTIONS ${A_LinkFlags})
     set_property(TARGET ${Target} APPEND PROPERTY INCLUDE_DIRECTORIES ${ENGINE_DIR} ${MOUNT_DIR} ${LIB_DIR})
     set_property(TARGET ${Target} APPEND PROPERTY COMPILE_DEFINITIONS ${A_Definitions})
     set_target_properties(${Target} PROPERTIES OUTPUT_NAME "${Executable}" PREFIX "" FOLDER "engine")
@@ -846,13 +847,14 @@ endmacro()
 
 function(AddApplication)
     set(oneValueArgs Target ExecutableName)
-    set(multiValueArgs ApplicationMain Definitions Flags CompileFeatures Files Libs Tests)
+    set(multiValueArgs ApplicationMain Definitions CompileFlags LinkFlags Files Libs Tests)
     cmake_parse_arguments(A "" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})
 
     # Reuse object files between the real application and the test one
     add_library(${A_Target}-objects OBJECT EXCLUDE_FROM_ALL ${A_Files} ${PCH_FILE})
     target_link_libraries(${A_Target}-objects engine-lib ${A_Libs} ${LIBS_BASE} ${CPP23SupportLibrary})
-    set_property(TARGET ${A_Target}-objects APPEND PROPERTY COMPILE_OPTIONS ${A_Flags})
+    set_property(TARGET ${A_Target}-objects APPEND PROPERTY COMPILE_OPTIONS ${A_CompileFlags})
+    set_property(TARGET ${A_Target}-objects APPEND PROPERTY LINK_OPTIONS ${A_LinkFlags})
     set_property(TARGET ${A_Target}-objects APPEND PROPERTY INCLUDE_DIRECTORIES ${ENGINE_DIR} ${MOUNT_DIR} ${LIB_DIR})
     set_property(TARGET ${A_Target}-objects APPEND PROPERTY COMPILE_DEFINITIONS ${A_Definitions})
 
@@ -893,8 +895,8 @@ if (NOT NACL)
             ExecutableName dummyapp
             Definitions USELESS_DEFINITION_TO_AVOID_PCH_ISSUE
             ApplicationMain ${ENGINE_DIR}/null/NullApplication.cpp
-            Flags ${WARNINGS}
-            Files ${COMMON_DIR}/Util.h  # must be nonempty
+            CompileFlags ${WARNINGS}
+            Files ${DUMMYAPPLIST}
             Tests ${ENGINETESTLIST}
         )
     endif()
@@ -920,7 +922,8 @@ if (BUILD_CLIENT)
         ExecutableName ${CLIENT_EXECUTABLE_NAME}
         ApplicationMain ${ENGINE_DIR}/client/ClientApplication.cpp
         Definitions ${Definitions}
-        Flags ${WARNINGS}
+        CompileFlags ${WARNINGS};${OPENMP_COMPILE_FLAG}
+        LinkFlags ${OPENMP_LINK_FLAG}
         Files ${WIN_RC} ${BUILDINFOLIST} ${QCOMMONLIST} ${SERVERLIST} ${CLIENTBASELIST} ${CLIENTLIST}
         Libs ${LIBS_CLIENT} ${LIBS_CLIENTBASE} ${LIBS_ENGINE}
         Tests ${CLIENTTESTLIST}
@@ -938,7 +941,7 @@ if (BUILD_SERVER)
         ExecutableName daemonded
         ApplicationMain ${ENGINE_DIR}/server/ServerApplication.cpp
         Definitions BUILD_ENGINE BUILD_SERVER
-        Flags ${WARNINGS}
+        CompileFlags ${WARNINGS}
         Files ${WIN_RC} ${BUILDINFOLIST} ${QCOMMONLIST} ${SERVERLIST} ${DEDSERVERLIST}
         Libs ${LIBS_ENGINE}
         Tests ${ENGINETESTLIST}
@@ -951,7 +954,7 @@ if (BUILD_TTY_CLIENT)
         ExecutableName daemon-tty
         ApplicationMain ${ENGINE_DIR}/client/ClientApplication.cpp
         Definitions BUILD_ENGINE BUILD_TTY_CLIENT
-        Flags ${WARNINGS}
+        CompileFlags ${WARNINGS}
         Files ${WIN_RC} ${BUILDINFOLIST} ${QCOMMONLIST} ${SERVERLIST} ${CLIENTBASELIST} ${TTYCLIENTLIST}
         Libs ${LIBS_CLIENTBASE} ${LIBS_ENGINE}
         Tests ${ENGINETESTLIST}

cmake/DaemonFlags.cmake

@@ -259,6 +259,10 @@ if (USE_FLOAT_EXCEPTIONS)
     add_definitions(-DDAEMON_USE_FLOAT_EXCEPTIONS)
 endif()
 
+if (NOT NACL AND BUILD_CLIENT)
+	option(USE_OPENMP "Use OpenMP to parallelize some tasks" OFF)
+endif()
+
 if (MSVC)
     set_c_cxx_flag("/MP")
 
@@ -267,6 +271,11 @@ if (MSVC)
         set_cxx_flag("/std:c++23preview")
     endif()
 
+	if (NOT NACL AND BUILD_CLIENT AND USE_OPENMP)
+		# Flag checks doen't work with MSVC so we assume it's there.
+		set(OPENMP_COMPILE_FLAG "/openmp")
+	endif()
+
     if (USE_FAST_MATH)
         set_c_cxx_flag("/fp:fast")
     else()
@@ -362,6 +371,17 @@ else()
 		endif()
 	endif()
 
+	if (NOT NACL AND BUILD_CLIENT AND USE_OPENMP)
+		check_CXX_compiler_flag("-fopenmp" FLAG_FOPENMP)
+
+		if (FLAG_FOPENMP)
+			set(OPENMP_COMPILE_FLAG "-fopenmp")
+			set(OPENMP_LINK_FLAG "-fopenmp")
+		else()
+			message(WARNING "Missing OpenMP")
+		endif()
+	endif()
+
 	if (NACL AND USE_NACL_SAIGO AND SAIGO_ARCH STREQUAL "arm")
 		# Saigo produces broken arm builds when optimizing them.
 		# See: https://github.com/Unvanquished/Unvanquished/issues/3297

src.cmake

@@ -188,6 +188,8 @@ set(ENGINELIST
     ${ENGINE_DIR}/framework/CvarSystem.h
     ${ENGINE_DIR}/framework/LogSystem.cpp
     ${ENGINE_DIR}/framework/LogSystem.h
+    ${ENGINE_DIR}/framework/OmpSystem.cpp
+    ${ENGINE_DIR}/framework/OmpSystem.h
     ${ENGINE_DIR}/framework/Resource.cpp
     ${ENGINE_DIR}/framework/Resource.h
     ${ENGINE_DIR}/framework/System.cpp
@@ -207,6 +209,11 @@ set(ENGINELIST
     ${ENGINE_DIR}/RefAPI.h
 )
 
+set(OMPLIST
+    ${ENGINE_DIR}/framework/OmpSystem.cpp
+    ${ENGINE_DIR}/framework/OmpSystem.h
+)
+
 if (WIN32)
     set(ENGINELIST ${ENGINELIST}
         ${ENGINE_DIR}/sys/con_passive.cpp
@@ -271,6 +278,7 @@ set(CLIENTBASELIST
 )
 
 set(CLIENTLIST
+    ${OMPLIST}
     ${ENGINE_DIR}/audio/ALObjects.cpp
     ${ENGINE_DIR}/audio/ALObjects.h
     ${ENGINE_DIR}/audio/Audio.cpp
@@ -304,16 +312,23 @@ set(CLIENTTESTLIST ${ENGINETESTLIST}
 )
 
 set(TTYCLIENTLIST
+    ${OMPLIST}
     ${ENGINE_DIR}/null/NullAudio.cpp
     ${ENGINE_DIR}/null/NullKeyboard.cpp
     ${ENGINE_DIR}/null/null_input.cpp
     ${ENGINE_DIR}/null/null_renderer.cpp
 )
 
 set(DEDSERVERLIST
+    ${OMPLIST}
     ${ENGINE_DIR}/null/NullKeyboard.cpp
     ${ENGINE_DIR}/null/null_client.cpp
     ${ENGINE_DIR}/null/null_input.cpp
 )
 
+set(DUMMYAPPLIST
+    ${OMPLIST}
+    ${COMMON_DIR}/Util.h
+)
+
 set(WIN_RC ${ENGINE_DIR}/sys/windows-resource/icon.rc)

src/engine/framework/OmpSystem.cpp

@@ -0,0 +1,108 @@
+/*
+===========================================================================
+Daemon BSD Source Code
+Copyright (c) 2025, Daemon Developers
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+    * Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+    * Redistributions in binary form must reproduce the above copyright
+      notice, this list of conditions and the following disclaimer in the
+      documentation and/or other materials provided with the distribution.
+    * Neither the name of the Daemon developers nor the
+      names of its contributors may be used to endorse or promote products
+      derived from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL DAEMON DEVELOPERS BE LIABLE FOR ANY
+DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+===========================================================================
+*/
+
+#include <algorithm>
+
+#include "CvarSystem.h"
+#include "OmpSystem.h"
+
+#if defined(_OPENMP)
+#include "omp.h"
+#endif
+
+#if defined(_OPENMP)
+static Cvar::Range<Cvar::Cvar<int>> common_ompThreads(
+	"common.ompThreads", "OpenMP threads", Cvar::NONE, 0, 0, 32 );
+#endif
+
+namespace Omp {
+#if defined(_OPENMP)
+static int ompMaxThreads = 1;
+#endif
+
+static int ompThreads = 1;
+
+static void ReadMaxThreads()
+{
+#if defined(_OPENMP)
+	ompMaxThreads = omp_get_max_threads();
+#endif
+}
+
+void EnlistThreads()
+{
+#if defined(_OPENMP)
+	omp_set_num_threads( ompThreads );
+#endif
+}
+
+void SetupThreads()
+{
+#if defined(_OPENMP)
+	if ( common_ompThreads.Get() )
+	{
+		ompThreads = common_ompThreads.Get();
+	}
+	else
+	{
+		switch( ompMaxThreads )
+		{
+			case 1:
+				ompThreads = 1;
+				break;
+			case 2:
+			case 3:
+				ompThreads = 2;
+				break;
+			default:
+				/* Using half threads than available is known to work best with:
+				- 2 threads on Low-end 4-cores (no SMP) Ryzen 3 3200G,
+				- 16 threads on High-end 16-cores/32-threads Ryzen Threadripper PRO 3955WX
+
+				It has not been tested on a system where ompMaxThreads / 2 > 16. */
+				ompThreads = std::min( ompMaxThreads / 2, 16 );
+		}
+	}
+#endif
+
+	EnlistThreads();
+}
+
+void Init()
+{
+	ReadMaxThreads();
+	SetupThreads();
+}
+
+int GetThreads()
+{
+	return ompThreads;
+}
+}

src/engine/framework/OmpSystem.h

@@ -0,0 +1,41 @@
+/*
+===========================================================================
+Daemon BSD Source Code
+Copyright (c) 2025, Daemon Developers
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+    * Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+    * Redistributions in binary form must reproduce the above copyright
+      notice, this list of conditions and the following disclaimer in the
+      documentation and/or other materials provided with the distribution.
+    * Neither the name of the Daemon developers nor the
+      names of its contributors may be used to endorse or promote products
+      derived from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL DAEMON DEVELOPERS BE LIABLE FOR ANY
+DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+===========================================================================
+*/
+
+#ifndef COMMON_OMP_SYSTEM_H_
+#define COMMON_OMP_SYSTEM_H_
+
+namespace Omp {
+void EnlistThreads();
+void SetupThreads();
+void Init();
+int GetThreads();
+};
+
+#endif // COMMON_OMP_SYSTEM_H_

src/engine/framework/System.cpp

@@ -34,6 +34,7 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include "ConsoleHistory.h"
 #include "CommandSystem.h"
 #include "LogSystem.h"
+#include "OmpSystem.h"
 #include "System.h"
 #include "CrashDump.h"
 #include "CvarSystem.h"
@@ -968,6 +969,8 @@ static void Init(int argc, char** argv)
 	for (auto& cvar: cmdlineArgs.cvars)
 		Cvar::SetValue(cvar.first, cvar.second);
 
+	Omp::Init();
+
 	// Load the console history
 	Console::History::Load();
 

src/engine/qcommon/common.cpp

@@ -47,6 +47,7 @@ Maryland 20850 USA.
 #include "framework/CommandSystem.h"
 #include "framework/CvarSystem.h"
 #include "framework/LogSystem.h"
+#include "framework/OmpSystem.h"
 #include "framework/System.h"
 #include "sys/sys_events.h"
 #include <common/FileSystem.h>
@@ -783,6 +784,8 @@ static Cvar::Cvar<bool> showTraceStats("common.showTraceStats", "are physics tra
 
 void Com_Frame()
 {
+	Omp::SetupThreads();
+
 	int             msec, minMsec;
 	static int      lastTime = 0;
 	//int             key;

src/engine/renderer/tr_backend.cpp

@@ -22,6 +22,7 @@ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
 // tr_backend.c
 
+#include "framework/OmpSystem.h"
 #include "tr_local.h"
 #include "gl_shader.h"
 #include "Material.h"
@@ -3954,6 +3955,8 @@ void RB_RenderThread()
 			return; // all done, renderer is shutting down
 		}
 
+		Omp::EnlistThreads();
+
 		renderThreadActive = true;
 
 		RB_ExecuteRenderCommands( data );

src/engine/renderer/tr_init.cpp

@@ -23,6 +23,7 @@ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 // tr_init.c -- functions that are not called every frame
 #include "tr_local.h"
 #include "framework/CvarSystem.h"
+#include "framework/OmpSystem.h"
 #include "DetectGLVendors.h"
 #include "Material.h"
 #include "GeometryCache.h"
@@ -1059,6 +1060,21 @@ ScreenshotCmd screenshotPNGRegistration("screenshotPNG", ssFormat_t::SSF_PNG, "p
 			Log::Notice("Using dual processor acceleration." );
 		}
 
+#if defined(_OPENMP)
+		int ompThreads = Omp::GetThreads();
+
+		if ( ompThreads == 1 )
+		{
+			Log::Notice("%sNot using OpenMP parallelism: only one thread.", Color::ToString( Color::Yellow ) );
+		}
+		else
+		{
+			Log::Notice("%sUsing OpenMP parallelism with %d threads.", Color::ToString( Color::Green ), ompThreads );
+		}
+#else
+		Log::Notice("%sNot using OpenMP parallelism: unavailable.", Color::ToString( Color::Yellow ) );
+#endif
+
 		if ( r_finish->integer )
 		{
 			Log::Notice("Forcing glFinish." );