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While we've taken advantage of split-sends in select situations, there are many other cases (such as sampler messages, framebuffer writes, and URB writes) that have never received that treatment, and continued to use monolithic send payloads. This commit introduces a new optimization pass which detects SEND messages with a single payload, finds an adjacent LOAD_PAYLOAD that produces that payload, splits it two, and updates the SEND to use both of the new smaller payloads. In places where we manually used split SENDS, we rely on underlying knowledge of the message to determine a natural split point. For example, header and data, or address and value. In this pass, we instead infer a natural split point by looking at the source registers. Often times, consecutive LOAD_PAYLOAD sources may already be grouped together in a contiguous block, such as a texture coordinate. Then, there is another bit of data, such as a LOD, that may come from elsewhere. We look for the point where the source list switches VGRFs, and split it there. (If there is a message header, we choose to split there, as it will naturally come from elsewhere.) This not only reduces the payload sizes, alleviating register pressure, but it means that we may be able to eliminate some payload construction altogether, if we have a contiguous block already and some extra data being tacked on to one side or the other. shader-db results for Icelake are: total instructions in shared programs: 19602513 -> 19369255 (-1.19%) instructions in affected programs: 6085404 -> 5852146 (-3.83%) helped: 23650 / HURT: 15 helped stats (abs) min: 1 max: 1344 x̄: 9.87 x̃: 3 helped stats (rel) min: 0.03% max: 35.71% x̄: 3.78% x̃: 2.15% HURT stats (abs) min: 1 max: 44 x̄: 7.20 x̃: 2 HURT stats (rel) min: 1.04% max: 20.00% x̄: 4.13% x̃: 2.00% 95% mean confidence interval for instructions value: -10.16 -9.55 95% mean confidence interval for instructions %-change: -3.84% -3.72% Instructions are helped. total cycles in shared programs: 848180368 -> 842208063 (-0.70%) cycles in affected programs: 599931746 -> 593959441 (-1.00%) helped: 22114 / HURT: 13053 helped stats (abs) min: 1 max: 482486 x̄: 580.94 x̃: 22 helped stats (rel) min: <.01% max: 78.92% x̄: 4.76% x̃: 0.75% HURT stats (abs) min: 1 max: 94022 x̄: 526.67 x̃: 22 HURT stats (rel) min: <.01% max: 188.99% x̄: 4.52% x̃: 0.61% 95% mean confidence interval for cycles value: -222.87 -116.79 95% mean confidence interval for cycles %-change: -1.44% -1.20% Cycles are helped. total spills in shared programs: 8387 -> 6569 (-21.68%) spills in affected programs: 5110 -> 3292 (-35.58%) helped: 359 / HURT: 3 total fills in shared programs: 11833 -> 8218 (-30.55%) fills in affected programs: 8635 -> 5020 (-41.86%) helped: 358 / HURT: 3 LOST: 1 SIMD16 shader, 659 SIMD32 shaders GAINED: 65 SIMD16 shaders, 959 SIMD32 shaders Total CPU time (seconds): 1505.48 -> 1474.08 (-2.09%) Examining these results: the few shaders where spills/fills increased were already spilling significantly, and were only slightly hurt. The applications affected were also helped in countless other shaders, and other shaders stopped spilling altogether or had 50% reductions. Many SIMD16 shaders were gained, and overall we gain more SIMD32, though many close to the register pressure line go back and forth. Reviewed-by: Francisco Jerez <currojerez@riseup.net> Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/17018> |
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`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.