Add a toggle to turn off vsync in Dawn

This commit add a toggle to turn off vsync in Dawn.
When turn off vsync, choose vulkan present mode VK_PRESENT_MODE_IMMEDIATE_KHR
if the mode is available on the system, but if the mode isn't supported,
choose default mode VK_PRESENT_MODE_FIFO_KHR.

BUG=dawn:237

Change-Id: If400262b67cc8051422745e3bed737431183c0b6
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/12100
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Austin Eng <enga@chromium.org>
Commit-Queue: Yizhou Jiang <yizhou.jiang@intel.com>

src/dawn_native/Toggles.cpp

@@ -57,6 +57,11 @@ namespace dawn_native {
                "Clears resource to zero on first usage. This initializes the resource "
                "so that no dirty bits from recycled memory is present in the new resource.",
                "https://bugs.chromium.org/p/dawn/issues/detail?id=145"}},
+             {Toggle::TurnOffVsync,
+              {"turn_off_vsync",
+               "Turn off vsync when rendering. In order to do performance test or run perf tests, "
+               "turn off vsync so that the fps can exeed 60.",
+               "https://bugs.chromium.org/p/dawn/issues/detail?id=237"}},
              {Toggle::UseTemporaryBufferInCompressedTextureToTextureCopy,
               {"use_temporary_buffer_in_texture_to_texture_copy",
                "Split texture-to-texture copy into two copies: copy from source texture into a "

src/dawn_native/Toggles.h

@@ -28,6 +28,7 @@ namespace dawn_native {
         NonzeroClearResourcesOnCreationForTesting,
         AlwaysResolveIntoZeroLevelAndLayer,
         LazyClearResourceOnFirstUse,
+        TurnOffVsync,
         UseTemporaryBufferInCompressedTextureToTextureCopy,
 
         EnumCount,

src/dawn_native/vulkan/NativeSwapChainImplVk.cpp

@@ -24,8 +24,30 @@ namespace dawn_native { namespace vulkan {
 
     namespace {
 
+        bool chooseSwapPresentMode(const std::vector<VkPresentModeKHR>& availablePresentModes,
+                                   bool turnOffVsync,
+                                   VkPresentModeKHR* presentMode) {
+            if (turnOffVsync) {
+                for (const auto& availablePresentMode : availablePresentModes) {
+                    if (availablePresentMode == VK_PRESENT_MODE_IMMEDIATE_KHR) {
+                        *presentMode = availablePresentMode;
+                        return true;
+                    }
+                }
+                return false;
+            }
+
+            *presentMode = VK_PRESENT_MODE_FIFO_KHR;
+            return true;
+        }
+
         bool ChooseSurfaceConfig(const VulkanSurfaceInfo& info,
-                                 NativeSwapChainImpl::ChosenConfig* config) {
+                                 NativeSwapChainImpl::ChosenConfig* config,
+                                 bool turnOffVsync) {
+            VkPresentModeKHR presentMode;
+            if (!chooseSwapPresentMode(info.presentModes, turnOffVsync, &presentMode)) {
+                return false;
+            }
             // TODO(cwallez@chromium.org): For now this is hardcoded to what works with one NVIDIA
             // driver. Need to generalize
             config->nativeFormat = VK_FORMAT_B8G8R8A8_UNORM;
@@ -35,11 +57,11 @@ namespace dawn_native { namespace vulkan {
             // TODO(cwallez@chromium.org): This is upside down compared to what we want, at least
             // on Linux
             config->preTransform = info.capabilities.currentTransform;
-            config->presentMode = VK_PRESENT_MODE_FIFO_KHR;
+            config->presentMode = presentMode;
             config->compositeAlpha = VK_COMPOSITE_ALPHA_OPAQUE_BIT_KHR;
+
             return true;
         }
-
     }  // anonymous namespace
 
     NativeSwapChainImpl::NativeSwapChainImpl(Device* device, VkSurfaceKHR surface)
@@ -63,7 +85,7 @@ namespace dawn_native { namespace vulkan {
             ASSERT(false);
         }
 
-        if (!ChooseSurfaceConfig(mInfo, &mConfig)) {
+        if (!ChooseSurfaceConfig(mInfo, &mConfig, mDevice->IsToggleEnabled(Toggle::TurnOffVsync))) {
             ASSERT(false);
         }
     }

src/tests/unittests/validation/ToggleValidationTests.cpp

@@ -75,4 +75,20 @@ TEST_F(ToggleValidationTest, OverrideToggleUsage) {
         ASSERT_EQ(InvalidToggleExists, false);
     }
 }
+
+TEST_F(ToggleValidationTest, TurnOffVsyncWithToggle) {
+    const char* kValidToggleName = "turn_off_vsync";
+    dawn_native::DeviceDescriptor descriptor;
+    descriptor.forceEnabledToggles.push_back(kValidToggleName);
+
+    DawnDevice deviceWithToggle = adapter.CreateDevice(&descriptor);
+    std::vector<const char*> toggleNames = dawn_native::GetTogglesUsed(deviceWithToggle);
+    bool validToggleExists = false;
+    for (const char* toggle : toggleNames) {
+        if (strcmp(toggle, kValidToggleName) == 0) {
+            validToggleExists = true;
+        }
+    }
+    ASSERT_EQ(validToggleExists, true);
+}
 }  // anonymous namespace