Residency Bug: Always Attempt To Evict To Under Budget

In the case that a previous submit to the GPU required Dawn to exceed
the residency budget, Dawn must attempt to get back under budget the
next time EnsureCanMakeResident is called. This CL fixes a bug where we
only evicted the current size needed to be resident, which would
incorrectly raise the budget when a submit to the GPU required us to
exceed the budget.

Bug: dawn:193
Change-Id: I04649056e9eecce1fc6b5759c889b52a4f1b4594
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/19440
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Austin Eng <enga@chromium.org>
Commit-Queue: Brandon Jones <brandon1.jones@intel.com>

src/dawn_native/d3d12/ResidencyManagerD3D12.cpp

@@ -171,9 +171,10 @@ namespace dawn_native { namespace d3d12 {
         }
 
         std::vector<ID3D12Pageable*> resourcesToEvict;
-
+        uint64_t sizeNeededToBeUnderBudget =
+            memoryUsageAfterMakeResident - mVideoMemoryInfo.dawnBudget;
         uint64_t sizeEvicted = 0;
-        while (sizeEvicted < sizeToMakeResident) {
+        while (sizeEvicted < sizeNeededToBeUnderBudget) {
             Heap* heap;
             DAWN_TRY_ASSIGN(heap, RemoveSingleEntryFromLRU());
 

src/tests/white_box/D3D12ResidencyTests.cpp

@@ -276,4 +276,29 @@ TEST_P(D3D12ResidencyTests, AsyncMappedBufferWrite) {
     EXPECT_FALSE(CheckIfBufferIsResident(buffer));
 }
 
+// Check that overcommitting in a single submit works, then make sure the budget is enforced after.
+TEST_P(D3D12ResidencyTests, OvercommitInASingleSubmit) {
+    // Create enough buffers to exceed the budget
+    constexpr uint32_t numberOfBuffersToOvercommit = 5;
+    std::vector<wgpu::Buffer> bufferSet1 = AllocateBuffers(
+        kDirectlyAllocatedResourceSize,
+        (kRestrictedBudgetSize / kDirectlyAllocatedResourceSize) + numberOfBuffersToOvercommit);
+    // Touch the buffers, which creates an overcommitted command list.
+    TouchBuffers(0, bufferSet1.size(), bufferSet1);
+    // Ensure that all of these buffers are resident, even though we're exceeding the budget.
+    for (uint32_t i = 0; i < bufferSet1.size(); i++) {
+        EXPECT_TRUE(CheckIfBufferIsResident(bufferSet1[i]));
+    }
+
+    // Allocate another set of buffers that exceeds the budget.
+    std::vector<wgpu::Buffer> bufferSet2 = AllocateBuffers(
+        kDirectlyAllocatedResourceSize,
+        (kRestrictedBudgetSize / kDirectlyAllocatedResourceSize) + numberOfBuffersToOvercommit);
+    // Ensure the first <numberOfBuffersToOvercommit> buffers in the second buffer set were evicted,
+    // since they shouldn't fit in the budget.
+    for (uint32_t i = 0; i < numberOfBuffersToOvercommit; i++) {
+        EXPECT_FALSE(CheckIfBufferIsResident(bufferSet2[i]));
+    }
+}
+
 DAWN_INSTANTIATE_TEST(D3D12ResidencyTests, D3D12Backend());