V-Sync Simulator

This is a simulator to help game developers (and other graphics developers where latency and performance matters, such as VR) and end users understand the effects of buffer_count and swapchain_count on different scenarios by providing an interactive interface.

These 2 settings are common to most engines based on modern APIs (Vulkan, D3D12, Metal).

• swapchain_count is the number of swapchains requested to the API. A value of 3 is traditionally known as triple buffer (1 front buffer + 2 back buffers).
• buffer_count is the number of frames the CPU can get ahead of the GPU before it needs to stall. Sometimes this is called "Render Ahead".
  • Note that value has little or nothing to do with "Render Ahead vs Triple Buffer" described in an old Anandtech article.
  • What Andandtech article describes as "Triple Buffer" can be can be achieved by setting buffer_count >= 1, swapchain_count >= 3 and V-Sync must be in MAILBOX mode (Vulkan nomenclature).
  • What Andandtech article describes as "Render Ahead Queue" can be can be achieved by setting buffer_count >= 1, swapchain_count >= 3 and V-Sync must be in FIFO mode (Vulkan nomenclature).

This simulator simulates worst-case latency when presenting assuming that:

• The CPU takes cpu_time +/- cpu_time_variance to prepare the commands. i.e. Randomized in range [cpu_time - cpu_time_variance; cpu_time + cpu_time_variance]
• The GPU takes gpu_time +/- gpu_time_variance to render (randomized)
• VSync is Enabled and in FIFO mode

The code is in C++ but there is a web interface through emscripten.

Try the simulator now.