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d5fb9cccdc
We'll start doing slow depth clears more often on HIZ_CCS buffers in a
future commit. Reduce the performance impact by making them use less
bandwidth.
From the Depth Test section of the BSpec:
This function is enabled by the Depth Test Enable state variable. If
enabled, the pixel's ("source") depth value is first computed. After
computation the pixel's depth value is clamped to the range defined
by Minimum Depth and Maximum Depth in the selected CC_VIEWPORT state.
Then the current ("destination") depth buffer value for this pixel is
read.
and from the Depth Buffer Updates section of the BSpec:
If depth testing is disabled or the depth test passed, the incoming
pixel's depth value is written to the Depth Buffer.
Taken together, it's clear that depth testing isn't necessary to perform
a depth buffer clear. Mark Janes and I analyzed this patch with
frameretrace and a depthrange piglit test. I disabled HiZ to ensure we'd
get slow depth clears. We've observed the bandwidth consumption by the
depth buffer access to be cut ~50% on BDW and SKL during depth clears.
On a more graphically intensive workload, the Shadowmapping Sascha
benchmark, I took the average of 3 runs on a BDW with a display
resolution of about 1920x1200 (minus some desktop environment
decorations). I measured a 22.61% FPS improvement when HiZ is disabled.
v2. The BSpec doesn't mandate this behavior, update comment accordingly.
(Ken)
Fixes:
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| .gitlab-ci | ||
| bin | ||
| build-support | ||
| docs | ||
| doxygen | ||
| include | ||
| scons | ||
| src | ||
| subprojects | ||
| .dir-locals.el | ||
| .editorconfig | ||
| .gitignore | ||
| .gitlab-ci.yml | ||
| .mailmap | ||
| .travis.yml | ||
| Android.common.mk | ||
| Android.mk | ||
| appveyor.yml | ||
| CleanSpec.mk | ||
| common.py | ||
| meson.build | ||
| meson_options.txt | ||
| README.rst | ||
| REVIEWERS | ||
| SConstruct | ||
| VERSION | ||
`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 email mailing-lists for patches submission, review and discussions.