Disable custom heaps when UMA is not supported.

include/gpgmm_d3d12.h

@@ -684,12 +684,13 @@ namespace gpgmm::d3d12 {
         */
         ALLOCATOR_FLAG_ALWAYS_ON_DEMAND = 0x8,
 
-        /** \brief Disables use of D3D12_HEAP_TYPE_CUSTOM.
+        /** \brief Disables using D3D12_HEAP_TYPE_CUSTOM-equivalent upload heap everywhere on UMA
+        GPUs.
 
-        Used to workaround issues when a custom-equivalent heap is not considered equal to
-        the corresponding heap type.
+        Used to workaround issues when custom heaps are not being recongized as expected or driver
+        bugs related to using a single memory pool.
         */
-        ALLOCATOR_FLAG_DISABLE_CUSTOM_HEAPS = 0x10,
+        ALLOCATOR_FLAG_DISABLE_UNIFIED_MEMORY = 0x10,
 
         /** \brief Report leaks of resource allocations.
 
@@ -974,7 +975,7 @@ namespace gpgmm::d3d12 {
         as well as frequent CPU reads would beneifit from D3D12_HEAP_TYPE_READBACK since the CPU
         properties are always write-combined.
 
-        If ALLOCATOR_FLAG_DISABLE_CUSTOM_HEAPS was specified, heap type was
+        If ALLOCATOR_FLAG_DISABLE_UNIFIED_MEMORY was specified, heap type was
         D3D12_HEAP_TYPE_READBACK, or the adapter is not cache-coherent UMA, this flag has no effect.
         */
         ALLOCATION_FLAG_ALWAYS_ATTRIBUTE_HEAPS = 0x20,

src/gpgmm/d3d12/ResourceAllocatorD3D12.cpp

@@ -476,6 +476,16 @@ namespace gpgmm::d3d12 {
             newDescriptor.SubAllocationAlgorithm = ALLOCATOR_ALGORITHM_SLAB;
         }
 
+        // By default, UMA is allowed to use a single heap type. Unless it is explicitly disabled or
+        // unsupported by the device.
+        if (!(allocatorDescriptor.Flags & ALLOCATOR_FLAG_DISABLE_UNIFIED_MEMORY) &&
+            !caps->IsAdapterCacheCoherentUMA()) {
+            gpgmm::DebugLog()
+                << "ALLOCATOR_FLAG_DISABLE_UNIFIED_MEMORY was not requested but enabled "
+                   "anyway because the device did not support cache-coherent UMA.";
+            newDescriptor.Flags |= ALLOCATOR_FLAG_DISABLE_UNIFIED_MEMORY;
+        }
+
         // Resource heap tier is required but user didn't specify one.
         if (newDescriptor.ResourceHeapTier == 0) {
             newDescriptor.ResourceHeapTier = caps->GetMaxResourceHeapTierSupported();
@@ -569,7 +579,7 @@ namespace gpgmm::d3d12 {
           mFlushEventBuffersOnDestruct(descriptor.RecordOptions.EventScope &
                                        EVENT_RECORD_SCOPE_PER_INSTANCE),
           mUseDetailedTimingEvents(descriptor.RecordOptions.UseDetailedTimingEvents),
-          mIsCustomHeapsDisabled(descriptor.Flags & ALLOCATOR_FLAG_DISABLE_CUSTOM_HEAPS) {
+          mIsCustomHeapsDisabled(descriptor.Flags & ALLOCATOR_FLAG_DISABLE_UNIFIED_MEMORY) {
         GPGMM_TRACE_EVENT_OBJECT_NEW(this);
 
         if (descriptor.Flags & ALLOCATOR_FLAG_NEVER_LEAK_MEMORY) {
@@ -938,7 +948,7 @@ namespace gpgmm::d3d12 {
         // read-back would be inefficent since upload heaps on UMA adapters are usually
         // write-combined (vs write-back) so leave read back heaps alone.
         if (!(allocationDescriptor.Flags & ALLOCATION_FLAG_ALWAYS_ATTRIBUTE_HEAPS) &&
-            mCaps->IsAdapterCacheCoherentUMA() && !mIsCustomHeapsDisabled) {
+            !mIsCustomHeapsDisabled) {
             if (allocationDescriptor.HeapType != D3D12_HEAP_TYPE_READBACK) {
                 heapType = D3D12_HEAP_TYPE_UPLOAD;
             } else {

src/tests/end2end/D3D12ResourceAllocatorTests.cpp

@@ -714,9 +714,9 @@ TEST_F(D3D12ResourceAllocatorTests, CreateBufferUMA) {
     EXPECT_EQ(resourceAllocator->GetStats().FreeMemoryUsage, kBufferOf4MBAllocationSize * 2);
 }
 
-TEST_F(D3D12ResourceAllocatorTests, CreateBufferDisableCustomHeaps) {
+TEST_F(D3D12ResourceAllocatorTests, CreateBufferDisableUMA) {
     ALLOCATOR_DESC allocatorDesc = CreateBasicAllocatorDesc();
-    allocatorDesc.Flags |= ALLOCATOR_FLAG_DISABLE_CUSTOM_HEAPS;
+    allocatorDesc.Flags |= ALLOCATOR_FLAG_DISABLE_UNIFIED_MEMORY;
 
     ComPtr<IResourceAllocator> resourceAllocator;
     ASSERT_SUCCEEDED(CreateResourceAllocator(allocatorDesc, &resourceAllocator, nullptr));