mirror_ubuntu-kernels/drivers/gpu
Chris Wilson 6b86f90019 drm/i915: Replace global bsd_dispatch_index with random seed
We keep a global seed for the legacy BSD round-robin selector, but in
our testing of multiple simultaneous client workloads, a random seed
spreads the load more evenly. (As even as an initial round-robin selector
can be!) Removing the global is one less variable we have to find a home
for!

We can simulate multi-client (both same and mixed workloads) using
igt/gem_wsim to work out optimal strategies and then compare our
simulation with the actual transcoder on multi-engine machines. This
fixed round-robin turns out to be one of the worst methods.

No user is advised to use this method; the current suggestion is to use
a virtual engine for agnostic batches, randomised submission or using
the busyness tracking to select the most idle engine at the time of
dispatch. At the present time, intel-media is explicit, but libva still
seems to use it, with the exception of batches that must execute on vcs0.
Oh well.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190809091010.23281-2-chris@chris-wilson.co.uk
2019-08-09 14:06:52 +01:00
..
drm drm/i915: Replace global bsd_dispatch_index with random seed 2019-08-09 14:06:52 +01:00
host1x drm/tegra: Changes for v5.3-rc1 2019-06-25 12:59:43 +10:00
ipu-v3 drm main pull request for v5.3-rc1 (sans mm changes) 2019-07-15 19:04:27 -07:00
vga topic/remove-fbcon-notifiers: 2019-06-26 12:26:34 +02:00
Makefile treewide: Add SPDX license identifier - Makefile/Kconfig 2019-05-21 10:50:46 +02:00