Vulkan requires the programmer to assure correct synchronization. Any commands submitted via a command buffer are generally allowed to be executed out-of-order. Pipeline barriers are necessary in certain situations to assure data required is in the correct layout and available when the graphics processor accesses it.

Resources considered Constants during Rendering

The below listed resources are considered constants during rendering, so you are not required to protect access to these with pipeline barriers

• Vertex and Index Buffer
• Scene Textures
• Scene Materials
• Geometry Meta Buffer

When and what to synchronize

• Sampled images and storage images require pipeline barriers protecting against read/write before access (unless they are considered constant). Use the ImageLayoutCache (member of FrameRenderInfo struct) to maintain image layout of images when your barriers transition the layout. The image layout must be cached so it can be set in the oldLayout field. If it is not set (left to VK_IMAGELAYOUT_UNDEFINED), the driver may discard all image data on layout transition.
• Storage and Uniform Buffers require pipeline barriers protecting against read/write before access (unless they are considered constant).