[Intel-gfx] [CI 1/2] drm/mm: Add an iterator to optimally walk over holes for an allocation (v4)

Tvrtko Ursulin tvrtko.ursulin at linux.intel.com
Mon Feb 28 10:34:57 UTC 2022


Hi Vivek,

On 27/02/2022 17:29, Vivek Kasireddy wrote:
> This iterator relies on drm_mm_first_hole() and drm_mm_next_hole()
> functions to identify suitable holes for an allocation of a given
> size by efficiently traversing the rbtree associated with the given
> allocator.
> 
> It replaces the for loop in drm_mm_insert_node_in_range() and can
> also be used by drm drivers to quickly identify holes of a certain
> size within a given range.
> 
> v2: (Tvrtko)
> - Prepend a double underscore for the newly exported first/next_hole
> - s/each_best_hole/each_suitable_hole/g
> - Mask out DRM_MM_INSERT_ONCE from the mode before calling
>    first/next_hole and elsewhere.
> 
> v3: (Tvrtko)
> - Reduce the number of hunks by retaining the "mode" variable name
> 
> v4:
> - Typo: s/__drm_mm_next_hole(.., hole/__drm_mm_next_hole(.., pos
> 
> Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> Acked-by: Christian König <christian.koenig at amd.com>
> Suggested-by: Tvrtko Ursulin <tvrtko.ursulin at linux.intel.com>
> Signed-off-by: Vivek Kasireddy <vivek.kasireddy at intel.com>
> ---
>   drivers/gpu/drm/drm_mm.c | 32 +++++++++++++++-----------------
>   include/drm/drm_mm.h     | 36 ++++++++++++++++++++++++++++++++++++
>   2 files changed, 51 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_mm.c b/drivers/gpu/drm/drm_mm.c
> index 8257f9d4f619..8efea548ae9f 100644
> --- a/drivers/gpu/drm/drm_mm.c
> +++ b/drivers/gpu/drm/drm_mm.c
> @@ -352,10 +352,10 @@ static struct drm_mm_node *find_hole_addr(struct drm_mm *mm, u64 addr, u64 size)
>   	return node;
>   }
>   
> -static struct drm_mm_node *
> -first_hole(struct drm_mm *mm,
> -	   u64 start, u64 end, u64 size,
> -	   enum drm_mm_insert_mode mode)
> +struct drm_mm_node *
> +__drm_mm_first_hole(struct drm_mm *mm,
> +		    u64 start, u64 end, u64 size,
> +		    enum drm_mm_insert_mode mode)
>   {
>   	switch (mode) {
>   	default:
> @@ -374,6 +374,7 @@ first_hole(struct drm_mm *mm,
>   						hole_stack);
>   	}
>   }
> +EXPORT_SYMBOL(__drm_mm_first_hole);
>   
>   /**
>    * DECLARE_NEXT_HOLE_ADDR - macro to declare next hole functions
> @@ -410,11 +411,11 @@ static struct drm_mm_node *name(struct drm_mm_node *entry, u64 size)	\
>   DECLARE_NEXT_HOLE_ADDR(next_hole_high_addr, rb_left, rb_right)
>   DECLARE_NEXT_HOLE_ADDR(next_hole_low_addr, rb_right, rb_left)
>   
> -static struct drm_mm_node *
> -next_hole(struct drm_mm *mm,
> -	  struct drm_mm_node *node,
> -	  u64 size,
> -	  enum drm_mm_insert_mode mode)
> +struct drm_mm_node *
> +__drm_mm_next_hole(struct drm_mm *mm,
> +		   struct drm_mm_node *node,
> +		   u64 size,
> +		   enum drm_mm_insert_mode mode)
>   {
>   	switch (mode) {
>   	default:
> @@ -432,6 +433,7 @@ next_hole(struct drm_mm *mm,
>   		return &node->hole_stack == &mm->hole_stack ? NULL : node;
>   	}
>   }
> +EXPORT_SYMBOL(__drm_mm_next_hole);
>   
>   /**
>    * drm_mm_reserve_node - insert an pre-initialized node
> @@ -516,11 +518,11 @@ int drm_mm_insert_node_in_range(struct drm_mm * const mm,
>   				u64 size, u64 alignment,
>   				unsigned long color,
>   				u64 range_start, u64 range_end,
> -				enum drm_mm_insert_mode mode)
> +				enum drm_mm_insert_mode caller_mode)
>   {
>   	struct drm_mm_node *hole;
>   	u64 remainder_mask;
> -	bool once;
> +	enum drm_mm_insert_mode mode = caller_mode & ~DRM_MM_INSERT_ONCE;
>   
>   	DRM_MM_BUG_ON(range_start > range_end);
>   
> @@ -533,13 +535,9 @@ int drm_mm_insert_node_in_range(struct drm_mm * const mm,
>   	if (alignment <= 1)
>   		alignment = 0;
>   
> -	once = mode & DRM_MM_INSERT_ONCE;
> -	mode &= ~DRM_MM_INSERT_ONCE;
> -
>   	remainder_mask = is_power_of_2(alignment) ? alignment - 1 : 0;
> -	for (hole = first_hole(mm, range_start, range_end, size, mode);
> -	     hole;
> -	     hole = once ? NULL : next_hole(mm, hole, size, mode)) {
> +	drm_mm_for_each_suitable_hole(hole, mm, range_start, range_end,
> +				      size, mode) {

I was doing one last read of the patch before I ask the maintainers 
where to merge it and realized - don't you need to pass in the 
caller_mode just here (not mode which has been masked out from "once")? 
Otherwise "once" mode will not be respected by the iterator.

Regards,

Tvrtko

>   		u64 hole_start = __drm_mm_hole_node_start(hole);
>   		u64 hole_end = hole_start + hole->hole_size;
>   		u64 adj_start, adj_end;
> diff --git a/include/drm/drm_mm.h b/include/drm/drm_mm.h
> index ac33ba1b18bc..dff6db627807 100644
> --- a/include/drm/drm_mm.h
> +++ b/include/drm/drm_mm.h
> @@ -400,6 +400,42 @@ static inline u64 drm_mm_hole_node_end(const struct drm_mm_node *hole_node)
>   	     1 : 0; \
>   	     pos = list_next_entry(pos, hole_stack))
>   
> +struct drm_mm_node *
> +__drm_mm_first_hole(struct drm_mm *mm,
> +		    u64 start, u64 end, u64 size,
> +		    enum drm_mm_insert_mode mode);
> +
> +struct drm_mm_node *
> +__drm_mm_next_hole(struct drm_mm *mm,
> +		   struct drm_mm_node *node,
> +		   u64 size,
> +		   enum drm_mm_insert_mode mode);
> +
> +/**
> + * drm_mm_for_each_suitable_hole - iterator to optimally walk over all
> + * holes that can fit an allocation of the given @size.
> + * @pos: &drm_mm_node used internally to track progress
> + * @mm: &drm_mm allocator to walk
> + * @range_start: start of the allowed range for the allocation
> + * @range_end: end of the allowed range for the allocation
> + * @size: size of the allocation
> + * @mode: fine-tune the allocation search
> + *
> + * This iterator walks over all holes suitable for the allocation of given
> + * @size in a very efficient manner. It is implemented by calling
> + * drm_mm_first_hole() and drm_mm_next_hole() which identify the
> + * appropriate holes within the given range by efficiently traversing the
> + * rbtree associated with @mm.
> + */
> +#define drm_mm_for_each_suitable_hole(pos, mm, range_start, range_end, \
> +				      size, mode) \
> +	for (pos = __drm_mm_first_hole(mm, range_start, range_end, size, \
> +				       mode & ~DRM_MM_INSERT_ONCE); \
> +	     pos; \
> +	     pos = mode & DRM_MM_INSERT_ONCE ? \
> +	     NULL : __drm_mm_next_hole(mm, pos, size, \
> +				       mode & ~DRM_MM_INSERT_ONCE))
> +
>   /*
>    * Basic range manager support (drm_mm.c)
>    */


More information about the Intel-gfx mailing list