Commits
Chris Wilson committed 6b86f90019c
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