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| author | Chris Wilson <chris@chris-wilson.co.uk> | 2019-08-09 11:10:09 +0200 |
|---|---|---|
| committer | Chris Wilson <chris@chris-wilson.co.uk> | 2019-08-09 15:06:52 +0200 |
| commit | 6b86f90019cf6286d0dc944f4bfd02c76db3b409 (patch) | |
| tree | a8f7af50fc3a2f146f988602071c584d29babddf | |
| parent | drm/i915: Check for a second VCS engine more carefully (diff) | |
| download | linux-6b86f90019cf6286d0dc944f4bfd02c76db3b409.tar.xz linux-6b86f90019cf6286d0dc944f4bfd02c76db3b409.zip | |
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
| -rw-r--r-- | drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c | 3 | ||||
| -rw-r--r-- | drivers/gpu/drm/i915/i915_drv.h | 3 | ||||
| -rw-r--r-- | drivers/gpu/drm/i915/i915_gem.c | 2 |
3 files changed, 1 insertions, 7 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; } diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h index dede70f9e671..71db63c583a9 100644 --- a/drivers/gpu/drm/i915/i915_drv.h +++ b/drivers/gpu/drm/i915/i915_drv.h @@ -749,9 +749,6 @@ struct i915_gem_mm { u64 unordered_timeline; - /* the indicator for dispatch video commands on two BSD rings */ - atomic_t bsd_engine_dispatch_index; - /** Bit 6 swizzling required for X tiling */ u32 bit_6_swizzle_x; /** Bit 6 swizzling required for Y tiling */ diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index 67a0bc4db9cd..6ff01a404346 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -1653,8 +1653,6 @@ int i915_gem_init_early(struct drm_i915_private *dev_priv) i915_gem_init__mm(dev_priv); i915_gem_init__pm(dev_priv); - atomic_set(&dev_priv->mm.bsd_engine_dispatch_index, 0); - spin_lock_init(&dev_priv->fb_tracking.lock); err = i915_gemfs_init(dev_priv); |