low_latency_layer

Important

As of v0.2.0, this layer is opt-in. Set LOW_LATENCY_LAYER=1 in your environment to enable it globally. Alternatively, this environment variable may be added to per-game Steam launch options to enable it on a case-by-case basis.

A C++23 implicit Vulkan layer that reduces click-to-photon latency.

Dependencies

• CMake: A cross-platform, open-source build system generator.
• Vulkan Headers: Vulkan header files and API registry.
• Vulkan Utility Libraries: Library to share code across various Vulkan repositories.

Building from Source and Installation

Clone this repo.

    $ git clone https://github.com/DatCaptainHorse/low_latency_layer-noapi
    $ cd low_latency_layer

Create an out-of-tree build directory (creatively we'll use 'build') and install.

⚠️ WARNING: You are likely going to have to install your distro's vulkan-headers, vulkan-utility-libraries, and possibly even cmake packages before proceeding. If you see an error here their absence is almost certainly the reason.

    $ cmake -B build ./
    $ cd ./build
    $ sudo make install

Usage and Configuration

Provided the layer was enabled with LOW_LATENCY_LAYER=1, most Vulkan titles should just.. work.

As long as your GPU supports VK_EXT_present_timing and generally modern Vulkan.. yep, no Reflex, no Anti-Lag, no XeLL or other vendor-junk.

Also there's a hotkey (for Linux only) Shift + F10 that toggles layer on/off as wanted. Give it a go!

Variable	Description
LOW_LATENCY_LAYER	Expose to enable the layer.
LOW_LATENCY_LAYER_MODE	off,drain,deadline - defaults to auto which picks deadline if VK_EXT_present_timing is available.
LOW_LATENCY_LAYER_FPS_LIMIT	Allow limiting FPS, defaults to 0 (uncapped)
LOW_LATENCY_LAYER_MARGIN_US	The amount of slack allowed for timing in microseconds, defaults to 1000.
LOW_LATENCY_LAYER_NO_PRESENT_TIMING	Force-disable VK_EXT_present_timing even if supported.
LOW_LATENCY_LAYER_QUEUE_DEPTH	How many frames can wait in queue, defaults to 0 which will lower FPS throughput, set to 1 if you want more FPS (at cost of latency).
LOW_LATENCY_LAYER_NO_TIMESTAMPS	Force-disable timestamp query injections, which cause a crash on exit in certain cases (harmless but annoying?).
LOW_LATENCY_LAYER_HOTKEY	Disable or change default hotkey, by default F10.
LOW_LATENCY_LAYER_START_DISABLED	The layer won't be active until toggled on by hotkey.
LOW_LATENCY_LAYER_DEBUG	Enable some debug logging and timing info dumps to stderr.
DISABLE_LOW_LATENCY_LAYER	Expose to disable the layer. This takes precedence over the LOW_LATENCY_LAYER enable environment variable.

Steam launch options example:

LOW_LATENCY_LAYER=1 %command%

Credits

This would have not been possible without the original work of https://github.com/Korthos-Software/low_latency_layer

Now everyone can enjoy, with every game :)

License

This project is licensed under the MIT License - see the LICENSE file for details.