In addition to working on new OpenCL performance optimizations, Red Hat engineer Karol Herbst just landed another important feature into Rusticl: OpenCL semaphores.
OpenCL semaphores are now supported by the Mesa 25.3-devel code with this Rust-based generic OpenCL driver for Gallium3D hardware drivers. OpenCL semaphores are important for work synchronization, especially when getting into interoperability with other external APIs. The cl_khr_semaphore, cl_khr_external_semaphore, and cl_khr_external_semaphore_sync_fd extensions are now wired up for the Rusticl driver. The synchronization object added by cl_semaphore_khr is much more effective, reusable and adaptable than the cl_event synchronization handling before it. The OpenCL semaphores support has been tested successfully across the Intel Iris, RadeonSI, and Zink Gallium3D drivers.
After the merge request was under review and revising the past month, the semaphores support for the Rusticl driver was merged on Sunday. Look for this and many other Rusticl improvements in Mesa 25.3 due out next quarter. If you missed it were also some recent Rusticl benchmarks on AMD Strix Halo and Intel Compute Runtime vs. Rusticl benchmarks too.
