Kenneth Graunke
1800e4b58c
(Co-authored with Chris Wilson.) Frequently, games create fences and later check them with a timeout of 0 to see if that work has completed yet. They do not want the work to be flushed immediately upon fence creation. This is what PIPE_FLUSH_DEFERRED does - it inhibits the flush at fence creation time, but still guarantees that a flush will occur later on once fence_finish() is called. Since syncpts can only occur at batch boundaries, when deferring a flush, we have to wait for the syncpt at the end of the batch being constructed. This is later than desired, but safe if blocking. To avoid extra delays, we additionally insert a PIPE_CONTROL to write an availability bit at the exact point of the fence. We can poll this on the CPU, allowing us to check whether the fence has gone by, even if the batch hasn't completed. It can also let us skip kernel calls. Improves performance in Bioshock Infinite by 10% on Icelake GT2 on -ForceCompatLevel=5 settings. Thanks to Felix Degrood and Mark Janes for helping notice the extraneous stalls and batches, Marek Olšák for adding deferred flush support to Gallium to solve this issue, and Chris Wilson for reworking a lot of the internals of this work. Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/3802>
`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.html <https://mesa3d.org/install.html>`_), but the recommended way is to use Meson (`docs/meson.html <https://mesa3d.org/meson.html>`_): .. code-block:: sh $ mkdir build $ cd build $ meson .. $ sudo ninja install Support ------- Many Mesa devs hang on IRC; if you're not sure which channel is appropriate, you should ask your question on `Freenode's #dri-devel <irc://chat.freenode.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.html <https://mesa3d.org/bugs.html>`_). Contributing ------------ Contributions are welcome, and step-by-step instructions can be found in our documentation (`docs/submittingpatches.html <https://mesa3d.org/submittingpatches.html>`_). Note that Mesa uses gitlab for patches submission, review and discussions.