Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> writes:
> Since a change in cache level is likely to trigger an unbind, avoid
> waiting under the mutex by preemptively doing an unlocked wait.
>
> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/i915/i915_gem.c | 29 +++++++++++++++++++----------
> 1 file changed, 19 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index c1c2765bb8d0..0926c291404c 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -3384,7 +3384,7 @@ int i915_gem_set_caching_ioctl(struct drm_device *dev, void *data,
> struct drm_i915_gem_caching *args = data;
> struct drm_i915_gem_object *obj;
> enum i915_cache_level level;
> - int ret;
> + int ret = 0;
>
> switch (args->caching) {
> case I915_CACHING_NONE:
> @@ -3409,20 +3409,29 @@ int i915_gem_set_caching_ioctl(struct drm_device *dev, void *data,
> return -EINVAL;
> }
>
> - ret = i915_mutex_lock_interruptible(dev);
> + obj = i915_gem_object_lookup(file, args->handle);
> + if (!obj)
> + return -ENOENT;
> +
> + if (obj->cache_level == level)
> + goto out;
> +
> + ret = i915_gem_object_wait(obj,
> + I915_WAIT_INTERRUPTIBLE,
> + MAX_SCHEDULE_TIMEOUT,
> + to_rps_client(file));
> if (ret)
> - return ret;
> + goto out;
>
> - obj = i915_gem_object_lookup(file, args->handle);
> - if (!obj) {
> - ret = -ENOENT;
> - goto unlock;
> - }
Is the intent here that you just make it very likely
that the wait in set_cache_level will not trigger?
-Mika
> + ret = i915_mutex_lock_interruptible(dev);
> + if (ret)
> + goto out;
>
> ret = i915_gem_object_set_cache_level(obj, level);
> - i915_gem_object_put(obj);
> -unlock:
> mutex_unlock(&dev->struct_mutex);
> +
> +out:
> + i915_gem_object_put(obj);
> return ret;
> }
>
> --
> 2.11.0
>
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