diff options
| author | Chris Wilson <chris@chris-wilson.co.uk> | 2019-08-09 10:10:09 +0100 |
|---|---|---|
| committer | Chris Wilson <chris@chris-wilson.co.uk> | 2019-08-09 14:06:52 +0100 |
| commit | 6b86f90019cf6286d0dc944f4bfd02c76db3b409 (patch) | |
| tree | a8f7af50fc3a2f146f988602071c584d29babddf /drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c | |
| parent | d5b2a3a4f85ad135123db8fc97ccdbf893546330 (diff) | |
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
Diffstat (limited to 'drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c')
| -rw-r--r-- | drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c index e3be6b039db7..50ca96f69ed6 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c @@ -2120,8 +2120,7 @@ gen8_dispatch_bsd_engine(struct drm_i915_private *dev_priv, /* Check whether the file_priv has already selected one ring. */ if ((int)file_priv->bsd_engine < 0) - file_priv->bsd_engine = atomic_fetch_xor(1, - &dev_priv->mm.bsd_engine_dispatch_index); + file_priv->bsd_engine = get_random_int() & 1; return file_priv->bsd_engine; } |