This reworks the intel_compute_pixel_hash_table_nway() pixel pipe
hashing table computation helper to handle cases where some pixel
pipes have processing power different from the others, this is helpful
for Gfx12.7+ platforms where there are pixel pipes with 1 DSS as well
as pixel pipes with 2 DSSes, which currently can lead to a serious
performance bottleneck in the pixel pipes with lower processing power.
In order to avoid such a load imbalance the
intel_compute_pixel_hash_table_nway() function will now take two pixel
pipe bitsets instead of one: Pixel pipes enabled on both bitsets will
appear with twice the frequency on the table as pixel pipes which only
appear on one bitset. See the comments below for more details on the
algorithm used to construct a pixel hashing table with the desired
properties.
With this change rendering performance improves by about 25% on a
fused MTL platform -- The list of specific configs this is expected to
show an improvement on is not included here since the list is rather
long and some of the configs may still be embargoed or may never be
productized, but in order to find out whether your Gfx12.7+ device
could be affected by this you can check the output of the
intel_dev_info tool from the Mesa tree and see if there are multiple
"pixel pipe" entries with different DSS count. That isn't expected to
occur on any DG2 configuration, only on MTL+ platforms, so this change
should have no effect at all on DG2 (it's easy to convince oneself
that it won't since for DG2 mask1 should equal mask2 so mask2 will be
set to zero at the beginning of intel_compute_pixel_hash_table_nway()
and the new swzx[] permutation will be set to the identity).
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/26266>
The coarser 32x32 cross-slice hashing mode seems to lead to better L1
and L2 utilization due to the improved execution locality, however it
can also lead to a bottleneck in a single slice, especially in
workloads that concentrate heavy rendering in small areas of the
screen (e.g. SynMark2 OglGeomPoint, OglTerrain*) -- This effect is
mitigated here by performing a permutation of the pixel pipe hashing
tables that ensures that adjacent rows map to pixel pipes as far away
as possible in the caching hierarchy.
Reviewed-by: Caio Oliveira <caio.oliveira@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/13569>
This starts off with the simplest possible pixel hashing table
calculation that just assigns consecutive indices (modulo N) to
adjacent entries of the table, along the lines of the existing
intel_compute_pixel_hash_table(). The same function will be improved
in a future commit with a more optimal calculation.
Reviewed-by: Caio Oliveira <caio.oliveira@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/13569>
In order to avoid some duplication between the GL and Vulkan driver,
which will get worse as we introduce additional code in order to
handle more recent generations.
Reviewed-by: Caio Oliveira <caio.oliveira@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/13569>
