Kenneth Graunke db34c71513 iris: Use more efficient binding table pointer formats on Icelake+.
Skylake and older use a 15:5 binding table pointer format, which means
our binder can be at most 64kB in size.  Each binding table within the
binder must be aligned to 32B.

XeHP uses a new 20:5 binding table format, which allows us to increase
the binder size to 1MB while retaining the nice 32B alignment.  Larger
binders mean fewer stalls as we update the base address for the binder.

Icelake and Tigerlake can either use the 15:5 format or an 18:8 format.
18:8 mode requires the base of each binding table to be aligned to 256B
instead of 32B, but it gives us a maximum binder size of 512kB.

We can store 64 binding table entries in a 256B chunk (256B / 4B = 64),
but only 8 entries in a 32B chunk (32B / 4B = 8).  Assuming that most
binding tables have fewer than 64 entries, this means that with the 18:8
format, we're likely to be able to fit 2048 (512KB / 256B) tables into a
a buffer before needing to allocate a new one and stall.

Technically, the old format could also store 2048 binding tables per
buffer as well (64KB / 32B = 2048).  However, tables that needed more
than 8 entries would need multiple 32B chunks.  A single table would
take multiple aligned chunks, while with the larger 256B format, it
could fit in a single one.

This cuts binder resets by 6.3% on a Shadow of Mordor benchmark trace.

Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/14507>
2022-03-09 09:18:59 +00:00
2022-03-04 16:05:10 -08:00
2022-01-19 15:17:17 +00:00
2022-02-02 22:49:09 +00:00

`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.
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