From 9c4763887deaed73059d390dbf4343e26e519873 Mon Sep 17 00:00:00 2001
From: German Semenov <GermanAizek@yandex.ru>
Date: Fri, 10 Nov 2023 18:33:53 +0300
Subject: [PATCH] Added NUMA architecture support for multiprocessig system

---
 src/xrCore/Threading/TaskManager.cpp | 51 ++++++++++++++++++++++++++++
 src/xrCore/Threading/TaskManager.hpp |  2 ++
 src/xrCore/_math.cpp                 |  5 +++
 3 files changed, 58 insertions(+)

diff --git a/src/xrCore/Threading/TaskManager.cpp b/src/xrCore/Threading/TaskManager.cpp
index 54859dcc900..53aa99c8ed5 100644
--- a/src/xrCore/Threading/TaskManager.cpp
+++ b/src/xrCore/Threading/TaskManager.cpp
@@ -213,12 +213,63 @@ void CalcIterations()
     ttapi_dwFastIter = u32((iterations * frequency) / ((end - start) * 50000));
 }
 
+// Lainon: This implementation supports both conventional single-cpu PC configurations
+// and multi-cpu system on NUMA architecture
+size_t NUMAHardwareConcurrency() noexcept
+{
+    size_t concurrency = 0;
+    DWORD length = 0;
+    if (GetLogicalProcessorInformationEx(RelationAll, nullptr, &length) != FALSE)
+    {
+        return concurrency;
+    }
+    if (GetLastError() != ERROR_INSUFFICIENT_BUFFER)
+    {
+        return concurrency;
+    }
+    std::unique_ptr<void, void (*)(void*)> buffer(std::malloc(length), std::free);
+    if (!buffer)
+    {
+        return concurrency;
+    }
+    auto* mem = reinterpret_cast<unsigned char*>(buffer.get());
+    if (GetLogicalProcessorInformationEx(
+            RelationAll, reinterpret_cast<PSYSTEM_LOGICAL_PROCESSOR_INFORMATION_EX>(mem), &length) == false)
+    {
+        return concurrency;
+    }
+    DWORD i = 0;
+    while (i < length)
+    {
+        const auto* proc = reinterpret_cast<PSYSTEM_LOGICAL_PROCESSOR_INFORMATION_EX>(mem + i);
+        if (proc->Processor.GroupCount <= 1) // single-proccessor configuration
+            return std::thread::hardware_concurrency();
+
+        if (proc->Relationship == RelationProcessorCore)
+        {
+            for (WORD group = 0; group < proc->Processor.GroupCount; ++group)
+            {
+                for (KAFFINITY mask = proc->Processor.GroupMask[group].Mask; mask != 0; mask >>= 1)
+                {
+                    concurrency += mask & 1;
+                }
+            }
+        }
+        i += proc->Size;
+    }
+    return concurrency;
+}
+
 TaskManager::TaskManager()
 {
     s_main_thread_worker = &s_tl_worker;
     s_main_thread_worker->id = 0;
 
+#if defined(XR_PLATFORM_WINDOWS)
+    const u32 threads = NUMAHardwareConcurrency() - OTHER_THREADS_COUNT;
+#else
     const u32 threads = std::thread::hardware_concurrency() - OTHER_THREADS_COUNT;
+#endif
     workers.reserve(threads);
     for (u32 i = 0; i < threads; ++i)
     {
diff --git a/src/xrCore/Threading/TaskManager.hpp b/src/xrCore/Threading/TaskManager.hpp
index d8fab683b0c..c54f5d107d7 100644
--- a/src/xrCore/Threading/TaskManager.hpp
+++ b/src/xrCore/Threading/TaskManager.hpp
@@ -18,6 +18,8 @@
 #include "Event.hpp"
 #include "Task.hpp"
 
+size_t NUMAHardwareConcurrency() noexcept;
+
 class TaskWorker;
 
 class XRCORE_API TaskManager final
diff --git a/src/xrCore/_math.cpp b/src/xrCore/_math.cpp
index 4414234e0a5..be0ab1e680a 100644
--- a/src/xrCore/_math.cpp
+++ b/src/xrCore/_math.cpp
@@ -1,6 +1,7 @@
 #include "stdafx.h"
 
 #if defined(XR_PLATFORM_WINDOWS)
+#   include "Threading/TaskManager.hpp"
 #   include <float.h> // _controlfp
 #   if defined(_M_FP_PRECISE)
 #       pragma fenv_access(on)
@@ -236,7 +237,11 @@ void _initialize_cpu()
     listFeature("AltiVec", SDL_HasAltiVec());
 
     Msg("* CPU features: %s", features);
+#if defined(XR_PLATFORM_WINDOWS)
+    Msg("* CPU threads: %d", NUMAHardwareConcurrency());
+#else
     Msg("* CPU threads: %d", std::thread::hardware_concurrency());
+#endif
 
     CPU::HasSSE = SDL_HasSSE(); // just in case, not sure if needed