[PATCH] drm/i915: Assert that the exec object lookup table is a power-of-two

[PATCH] drm/i915: Assert that the exec object lookup table is a power-of-two

[Chris Wilson]

As we make the simplification of using a power-of-two size for the
execbuffer handle-to-object TLB, we should validate that this is actually
true and so clarify that premise.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_gem_execbuffer.c |    1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index 8186f63..6a2f3e5 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -44,6 +44,7 @@ eb_create(int size)
 {
 	struct eb_objects *eb;
 	int count = PAGE_SIZE / sizeof(struct hlist_head) / 2;
+	BUILD_BUG_ON(!is_power_of_2(PAGE_SIZE / sizeof(struct hlist_head)));
 	while (count > size)
 		count >>= 1;
 	eb = kzalloc(count*sizeof(struct hlist_head) +
-- 
1.7.10.4

Re: [PATCH] drm/i915: Assert that the exec object lookup table is a power-of-two

[Daniel Vetter]

On Tue, Sep 18, 2012 at 10:04:02AM +0100, Chris Wilson wrote:
> As we make the simplification of using a power-of-two size for the
> execbuffer handle-to-object TLB, we should validate that this is actually
> true and so clarify that premise.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Queued for -next, thanks for the patch.
-Daniel

> ---
>  drivers/gpu/drm/i915/i915_gem_execbuffer.c |    1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> index 8186f63..6a2f3e5 100644
> --- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> +++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> @@ -44,6 +44,7 @@ eb_create(int size)
>  {
>  	struct eb_objects *eb;
>  	int count = PAGE_SIZE / sizeof(struct hlist_head) / 2;
> +	BUILD_BUG_ON(!is_power_of_2(PAGE_SIZE / sizeof(struct hlist_head)));
>  	while (count > size)
>  		count >>= 1;
>  	eb = kzalloc(count*sizeof(struct hlist_head) +
> -- 
> 1.7.10.4
> 
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch