From 236f3717c76bf02fb94c6c5dc45e3dcb71ed48e3 Mon Sep 17 00:00:00 2001
From: Egor Yusov <egor.yusov@gmail.com>
Date: Tue, 19 Mar 2019 00:32:11 -0700
Subject: Fixed issue with staging allocations in Vulkan backend on Integrated
 GPUs

---
 .../include/VulkanUtilities/VulkanMemoryManager.h  | 28 +++++++++++++++++++++-
 .../src/VulkanUtilities/VulkanMemoryManager.cpp    | 12 ++++++++--
 2 files changed, 37 insertions(+), 3 deletions(-)

(limited to 'Graphics/GraphicsEngineVulkan')

diff --git a/Graphics/GraphicsEngineVulkan/include/VulkanUtilities/VulkanMemoryManager.h b/Graphics/GraphicsEngineVulkan/include/VulkanUtilities/VulkanMemoryManager.h
index 45806642..4092db05 100644
--- a/Graphics/GraphicsEngineVulkan/include/VulkanUtilities/VulkanMemoryManager.h
+++ b/Graphics/GraphicsEngineVulkan/include/VulkanUtilities/VulkanMemoryManager.h
@@ -33,6 +33,7 @@
 #include "VulkanUtilities/VulkanPhysicalDevice.h"
 #include "VulkanUtilities/VulkanLogicalDevice.h"
 #include "VulkanUtilities/VulkanObjectWrappers.h"
+#include "HashUtils.h"
 
 namespace VulkanUtilities
 {
@@ -199,7 +200,32 @@ protected:
     Diligent::IMemoryAllocator& m_Allocator;
 
     std::mutex m_PagesMtx;
-    std::unordered_multimap<uint32_t, VulkanMemoryPage> m_Pages;
+    struct MemoryPageIndex
+    {
+        const uint32_t MemoryTypeIndex;
+        const bool     IsHostVisible;
+
+        MemoryPageIndex(uint32_t _MemoryTypeIndex,
+                        bool     _IsHostVisible) : 
+            MemoryTypeIndex(_MemoryTypeIndex),
+            IsHostVisible  (_IsHostVisible)
+        {}
+
+        bool operator == (const MemoryPageIndex& rhs)const
+        {
+            return MemoryTypeIndex == rhs.MemoryTypeIndex &&
+                   IsHostVisible   == rhs.IsHostVisible;
+        }
+
+        struct Hasher
+        {
+            size_t operator()(const MemoryPageIndex& PageIndex)const
+            {
+                return Diligent::ComputeHash(PageIndex.MemoryTypeIndex, PageIndex.IsHostVisible);
+            }
+        };
+    };
+    std::unordered_multimap<MemoryPageIndex, VulkanMemoryPage, MemoryPageIndex::Hasher> m_Pages;
     
     const VkDeviceSize m_DeviceLocalPageSize;
     const VkDeviceSize m_HostVisiblePageSize;
diff --git a/Graphics/GraphicsEngineVulkan/src/VulkanUtilities/VulkanMemoryManager.cpp b/Graphics/GraphicsEngineVulkan/src/VulkanUtilities/VulkanMemoryManager.cpp
index fd597327..870b00cb 100644
--- a/Graphics/GraphicsEngineVulkan/src/VulkanUtilities/VulkanMemoryManager.cpp
+++ b/Graphics/GraphicsEngineVulkan/src/VulkanUtilities/VulkanMemoryManager.cpp
@@ -135,8 +135,16 @@ VulkanMemoryAllocation VulkanMemoryManager::Allocate(VkDeviceSize Size, VkDevice
 {
     VulkanMemoryAllocation Allocation;
 
+    // On integrated GPUs, there is no difference between host-visible and GPU-only
+    // memory, so MemoryTypeIndex is the same. As GPU-only pages do not have CPU address, 
+    // we need to use HostVisible flag to differentiate the two.
+    // It is likely a good idea to always keep staging pages separate to reduce fragmenation 
+    // even though on integrated GPUs same pages can be used for both GPU-only and staging 
+    // allocations. Staging allocations are short-living and will be released when upload is 
+    // complete, while GPU-only allocations are expected to be long-living.
+    MemoryPageIndex PageIdx{MemoryTypeIndex, HostVisible};
     std::lock_guard<std::mutex> Lock(m_PagesMtx);
-    auto range = m_Pages.equal_range(MemoryTypeIndex);
+    auto range = m_Pages.equal_range(PageIdx);
     for(auto page_it = range.first; page_it != range.second; ++page_it)
     {
         Allocation = page_it->second.Allocate(Size, Alignment);
@@ -154,7 +162,7 @@ VulkanMemoryAllocation VulkanMemoryManager::Allocate(VkDeviceSize Size, VkDevice
         m_CurrAllocatedSize[stat_ind] += PageSize;
         m_PeakAllocatedSize[stat_ind] = std::max(m_PeakAllocatedSize[stat_ind], m_CurrAllocatedSize[stat_ind]);
 
-        auto it = m_Pages.emplace(MemoryTypeIndex, VulkanMemoryPage{*this, PageSize, MemoryTypeIndex, HostVisible});
+        auto it = m_Pages.emplace(PageIdx, VulkanMemoryPage{*this, PageSize, MemoryTypeIndex, HostVisible});
         LOG_INFO_MESSAGE("VulkanMemoryManager '", m_MgrName, "': created new ", (HostVisible ? "host-visible" : "device-local"), 
                          " page. (", Diligent::FormatMemorySize(PageSize, 2), ", type idx: ", MemoryTypeIndex, 
                          "). Current allocated size: ", Diligent::FormatMemorySize(m_CurrAllocatedSize[stat_ind], 2));
-- 
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