drm/radeon: add buffers to the LRU list from smallest to largest

Signed-off-by: Marek Olšák <marek.olsak@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>

diff --git a/drivers/gpu/drm/radeon/radeon_cs.c b/drivers/gpu/drm/radeon/radeon_cs.c
index f28a8d82fa19e1d49e21ff43837e01c21b578065..d49a3f705e490ba1adc120f3cd9a7040c8aed3c7 100644 (file)
--- a/drivers/gpu/drm/radeon/radeon_cs.c
+++ b/drivers/gpu/drm/radeon/radeon_cs.c
@@ -24,6 +24,7 @@
  * Authors:
  *    Jerome Glisse <glisse@freedesktop.org>
  */
+#include <linux/list_sort.h>
 #include <drm/drmP.h>
 #include <drm/radeon_drm.h>
 #include "radeon_reg.h"
@@ -290,6 +291,16 @@ int radeon_cs_parser_init(struct radeon_cs_parser *p, void *data)
        return 0;
 }
 
+static int cmp_size_smaller_first(void *priv, struct list_head *a,
+                                 struct list_head *b)
+{
+       struct radeon_bo_list *la = list_entry(a, struct radeon_bo_list, tv.head);
+       struct radeon_bo_list *lb = list_entry(b, struct radeon_bo_list, tv.head);
+
+       /* Sort A before B if A is smaller. */
+       return (int)la->bo->tbo.num_pages - (int)lb->bo->tbo.num_pages;
+}
+
 /**
  * cs_parser_fini() - clean parser states
  * @parser:    parser structure holding parsing context.
@@ -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);