Re: [Intel-gfx] [PATCH 28/38] drm/i915: Remove pinned check from madvise ioctl

[Daniel Vetter]

On Fri, Jun 03, 2016 at 05:55:43PM +0100, Chris Wilson wrote:
> We don't need to incur the overhead of checking whether the object is
> pinned prior to changing its madvise. If the object is pinned, the
> madvise will not take effect until it is unpinned and so we cannot free
> the pages being pointed at by hardware. Marking a pinned object with
> allocated pages as DONTNEED will not trigger any undue warnings. The check
> is therefore superfluous, and by removing it we can remove a linear walk
> over all the vma the object has.
> 
> Signed-off-by: Chris Wilson 

Needs lots of testing, but in principle I've become accustomed to this
idea meanwhile ;-)

Reviewed-by: Daniel Vetter 

> ---
>  drivers/gpu/drm/i915/i915_gem.c | 6 --
>  1 file changed, 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index b78f9df1894c..dad00800aeef 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -3600,11 +3600,6 @@ i915_gem_madvise_ioctl(struct drm_device *dev, void 
> *data,
>   goto unlock;
>   }
>  
> - if (i915_gem_obj_is_pinned(obj)) {
> - ret = -EINVAL;
> - goto out;
> - }
> -
>   if (obj->pages &&
>   obj->tiling_mode != I915_TILING_NONE &&
>   dev_priv->quirks & QUIRK_PIN_SWIZZLED_PAGES) {
> @@ -3623,7 +3618,6 @@ i915_gem_madvise_ioctl(struct drm_device *dev, void 
> *data,
>  
>   args->retained = obj->madv != __I915_MADV_PURGED;
>  
> -out:
>   i915_gem_object_put(obj);
>  unlock:
>   mutex_unlock(>struct_mutex);
> -- 
> 2.8.1
> 
> ___
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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[Intel-gfx] [PATCH 28/38] drm/i915: Remove pinned check from madvise ioctl

[Chris Wilson]

We don't need to incur the overhead of checking whether the object is
pinned prior to changing its madvise. If the object is pinned, the
madvise will not take effect until it is unpinned and so we cannot free
the pages being pointed at by hardware. Marking a pinned object with
allocated pages as DONTNEED will not trigger any undue warnings. The check
is therefore superfluous, and by removing it we can remove a linear walk
over all the vma the object has.

Signed-off-by: Chris Wilson 
---
 drivers/gpu/drm/i915/i915_gem.c | 6 --
 1 file changed, 6 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index b78f9df1894c..dad00800aeef 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -3600,11 +3600,6 @@ i915_gem_madvise_ioctl(struct drm_device *dev, void 
*data,
goto unlock;
}
 
-   if (i915_gem_obj_is_pinned(obj)) {
-   ret = -EINVAL;
-   goto out;
-   }
-
if (obj->pages &&
obj->tiling_mode != I915_TILING_NONE &&
dev_priv->quirks & QUIRK_PIN_SWIZZLED_PAGES) {
@@ -3623,7 +3618,6 @@ i915_gem_madvise_ioctl(struct drm_device *dev, void *data,
 
args->retained = obj->madv != __I915_MADV_PURGED;
 
-out:
i915_gem_object_put(obj);
 unlock:
mutex_unlock(>struct_mutex);
-- 
2.8.1

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