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authorChris Wilson <chris@chris-wilson.co.uk>2016-10-28 15:58:42 +0300
committerChris Wilson <chris@chris-wilson.co.uk>2016-10-28 22:53:49 +0300
commitfbbd37b36fa5e16a03aca07a922192d3db28588d (patch)
tree57e390a37058d0648818e6b96eb0769b90cd57f9 /drivers/gpu/drm/i915/i915_gem_tiling.c
parent40e62d5d6be8b4999068da31ee6aca7ca76669ee (diff)
downloadlinux-fbbd37b36fa5e16a03aca07a922192d3db28588d.tar.xz
drm/i915: Move object release to a freelist + worker
We want to hide the latency of releasing objects and their backing storage from the submission, so we move the actual free to a worker. This allows us to switch to struct_mutex freeing of the object in the next patch. Furthermore, if we know that the object we are dereferencing remains valid for the duration of our access, we can forgo the usual synchronisation barriers and atomic reference counting. To ensure this we defer freeing an object til after an RCU grace period, such that any lookup of the object within an RCU read critical section will remain valid until after we exit that critical section. We also employ this delay for rate-limiting the serialisation on reallocation - we have to slow down object creation in order to prevent resource starvation (in particular, files). v2: Return early in i915_gem_tiling() ioctl to skip over superfluous work on error. Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/20161028125858.23563-19-chris@chris-wilson.co.uk
Diffstat (limited to 'drivers/gpu/drm/i915/i915_gem_tiling.c')
-rw-r--r--drivers/gpu/drm/i915/i915_gem_tiling.c21
1 files changed, 13 insertions, 8 deletions
diff --git a/drivers/gpu/drm/i915/i915_gem_tiling.c b/drivers/gpu/drm/i915/i915_gem_tiling.c
index 6608799ee1f9..c63a9cf4da33 100644
--- a/drivers/gpu/drm/i915/i915_gem_tiling.c
+++ b/drivers/gpu/drm/i915/i915_gem_tiling.c
@@ -325,12 +325,19 @@ i915_gem_get_tiling(struct drm_device *dev, void *data,
struct drm_i915_gem_get_tiling *args = data;
struct drm_i915_private *dev_priv = to_i915(dev);
struct drm_i915_gem_object *obj;
+ int err = -ENOENT;
+
+ rcu_read_lock();
+ obj = i915_gem_object_lookup_rcu(file, args->handle);
+ if (obj) {
+ args->tiling_mode =
+ READ_ONCE(obj->tiling_and_stride) & TILING_MASK;
+ err = 0;
+ }
+ rcu_read_unlock();
+ if (unlikely(err))
+ return err;
- obj = i915_gem_object_lookup(file, args->handle);
- if (!obj)
- return -ENOENT;
-
- args->tiling_mode = READ_ONCE(obj->tiling_and_stride) & TILING_MASK;
switch (args->tiling_mode) {
case I915_TILING_X:
args->swizzle_mode = dev_priv->mm.bit_6_swizzle_x;
@@ -338,11 +345,10 @@ i915_gem_get_tiling(struct drm_device *dev, void *data,
case I915_TILING_Y:
args->swizzle_mode = dev_priv->mm.bit_6_swizzle_y;
break;
+ default:
case I915_TILING_NONE:
args->swizzle_mode = I915_BIT_6_SWIZZLE_NONE;
break;
- default:
- DRM_ERROR("unknown tiling mode\n");
}
/* Hide bit 17 from the user -- see comment in i915_gem_set_tiling */
@@ -355,6 +361,5 @@ i915_gem_get_tiling(struct drm_device *dev, void *data,
if (args->swizzle_mode == I915_BIT_6_SWIZZLE_9_10_17)
args->swizzle_mode = I915_BIT_6_SWIZZLE_9_10;
- i915_gem_object_put_unlocked(obj);
return 0;
}