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On non-LLC systems, most system memory isn't coherent between the CPU and GPU by default. However, we can enable snooping or 1-way coherency at a performance cost. In the old days, we maintained one set of cache buckets and toggled coherency as needed via I915_GEM_SET_CACHING. But in the modern uAPI (GEM_CREATE_EXT_SET_PAT) we have to select coherency up front at BO creation time. So this doesn't work out well anymore. This patch splits system memory into two distinct heaps: - IRIS_HEAP_SYSTEM_MEMORY_CACHED_COHERENT - IRIS_HEAP_SYSTEM_MEMORY_UNCACHED The flags_to_heap() function will select a heap for a given allocation based on the coherency/scanout requirements, as well as the hardware configuration (LLC integrated, non-LLC integrated, or discrete card). Once a heap is selected, it completely determines the cacheability and coherency settings. A given heap will always have the same mmap mode and PAT index. This enables us to simplify a lot of code. Because each heap also has its own bucket cache, we no longer have to disable bucket caching based on flags, cacheability, coherency, mmap modes, or so on, as all BOs in each cache have matching settings. This effectively enables bucket-caching for non-LLC systems. Reviewed-by: José Roberto de Souza <jose.souza@intel.com> Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/25447>
`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.