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The entire point of resource shadowing is to avoid unnecessary flushing. Flushing readers after shadowing is counterproductive. A refresher on how resource shadowing is supposed to work: First, we determine if it's beneficial to shadow resources. If so, we create a new backing buffer object. We flush the current writer of the resource, if there is one, so the current contents become known to the CPU. If we are not discarding the original resource, we then copy the existing contents of the buffer to the new shadow buffer on the CPU. Finally, we swap the resource's backing buffer for our shadow. Any batch that reads the resource will continue to read the old copy of the resource, and any future draw calls will see the new copy with the change implemented. Where did we go wrong? In988d5aae74("panfrost: Flush resources when shadowing"), we started flushing all readers. We didn't actually need to flush, we just needed to avoid dangling references on the batches reading the old copy of the resource. But that's easily enough avoided: just remove the references. The batches still hold a reference to the underlying BO, which will be freed at the right time regardless. Originally motivated by glmark2 -bbuffer:update-method=subdata, which has some pathological access paterns. Firefox is a lot faster anecdotally (now scrolling at 60fps in firefox). But what actually motivated this is an apitrace from Duckstation's GLES renderer. With this patch, the in-game portion is improved 3fps to 21fps. Closes: #4028 Fixes:988d5aae74("panfrost: Flush resources when shadowing") Signed-off-by: Alyssa Rosenzweig <alyssa@collabora.com> Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/19361> (cherry picked from commit2d8f28df73)
`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://mesa3d.org/install.html>`_), but the recommended way is to use Meson (`docs/meson.rst <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 `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://mesa3d.org/bugs.html>`_). Contributing ------------ Contributions are welcome, and step-by-step instructions can be found in our documentation (`docs/submittingpatches.rst <https://mesa3d.org/submittingpatches.html>`_). Note that Mesa uses gitlab for patches submission, review and discussions.