ca1533cd03
The Intel Gfx12.x generation of GPU has an architecture feature called EU fusion in which 2 subgroups run lock step. A typical case where this happens is a compute shader with 1x1x1 local workgroup size and a dispatch command of 2x1x1. In that case 2 threads will be run in lock step for each of the workgroup. This has been the sources of some troubles in the backend because one subgroup can run with all lanes disabled, requiring care for SEND messages using the NoMask flag (execution regardless of the lane mask). We found out that other things are happening when 2 subgroups run together : - the HW will use the surface/sampler handle from only one subgroup - the HW will use the sampler header from only one subgroup So one of the fused subgroup can access the wrong surface/sampler if the value is different between the 2 subgroups and that can happen even with subgroup uniform values. Fortunately we can flag SEND instructions to disable the fusion behavior (most likely at a performance cost). This change introduce a new divergence mode that tries to compute things divergent between subgroups so that we can flag instructions accordingly. Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com> Reviewed-by: Francisco Jerez <currojerez@riseup.net> Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/37394>
`Mesa <https://mesa3d.org>`_ - The 3D Graphics Library ====================================================== Source ------ This repository lives at https://gitlab.freedesktop.org/mesa/mesa. Other repositories are likely forks, and code found there is not supported. Build & install --------------- You can find more information in our documentation (`docs/install.rst <https://docs.mesa3d.org/install.html>`_), but the recommended way is to use Meson (`docs/meson.rst <https://docs.mesa3d.org/meson.html>`_): .. code-block:: sh $ meson setup build $ ninja -C build/ $ sudo ninja -C build/ install Support ------- Many Mesa devs hang on IRC; if you're not sure which channel is appropriate, you should ask your question on `OFTC's #dri-devel <irc://irc.oftc.net/dri-devel>`_, someone will redirect you if necessary. Remember that not everyone is in the same timezone as you, so it might take a while before someone qualified sees your question. To figure out who you're talking to, or which nick to ping for your question, check out `Who's Who on IRC <https://dri.freedesktop.org/wiki/WhosWho/>`_. The next best option is to ask your question in an email to the mailing lists: `mesa-dev\@lists.freedesktop.org <https://lists.freedesktop.org/mailman/listinfo/mesa-dev>`_ Bug reports ----------- If you think something isn't working properly, please file a bug report (`docs/bugs.rst <https://docs.mesa3d.org/bugs.html>`_). Contributing ------------ Contributions are welcome, and step-by-step instructions can be found in our documentation (`docs/submittingpatches.rst <https://docs.mesa3d.org/submittingpatches.html>`_). Note that Mesa uses gitlab for patches submission, review and discussions.