[PATCH 4/6] drm/radeon: add buffers to the LRU list from smallest to largest

[Michel Dänzer]

On Mit, 2014-02-26 at 19:25 +0100, Marek Olšák wrote:
> 
> diff --git a/drivers/gpu/drm/radeon/radeon_cs.c b/drivers/gpu/drm/radeon/radeon_cs.c
> index f28a8d8..d49a3f7 100644
> --- a/drivers/gpu/drm/radeon/radeon_cs.c
> +++ b/drivers/gpu/drm/radeon/radeon_cs.c
> [...]
> @@ -303,6 +314,18 @@ static void radeon_cs_parser_fini(struct radeon_cs_parser *parser, int error, bo
>  	unsigned i;
>  
>  	if (!error) {
> +		/* Sort the buffer list from the smallest to largest buffer,
> +		 * which affects the order of buffers in the LRU list.
> +		 * This assures that the smallest buffers are added first
> +		 * to the LRU list, so they are likely to be later evicted
> +		 * first, instead of large buffers whose eviction is more
> +		 * expensive.
> +		 *
> +		 * This slightly lowers the number of bytes moved by TTM
> +		 * per frame under memory pressure.
> +		 */
> +		list_sort(NULL, &parser->validated, cmp_size_smaller_first);
> +
>  		ttm_eu_fence_buffer_objects(&parser->ticket,
>  					    &parser->validated,
>  					    parser->ib.fence);

This seems like a good idea in general, so maybe it should be done in
ttm_eu_fence_buffer_objects() instead, and possibly also in the callers
of ttm_eu_backoff_reservation_locked().


-- 
Earthling Michel Dänzer            |                  http://www.amd.com
Libre software enthusiast          |                Mesa and X developer