panfrost: Add madvise support to BO cache

The kernel now supports madvise ioctl to indicate which BOs can be freed
when there is memory pressure. Mark BOs purgeable when they are in the
BO cache. The BOs must also be munmapped when they are in the cache or
they cannot be purged.

We could optimize avoiding the madvise ioctl on older kernels once the
driver version bump lands, but probably not worth it given the other
driver features also being added.

Reviewed-by: Alyssa Rosenzweig <[email protected]>
Reviewed-by: Tomeu Vizoso <[email protected]>
Signed-off-by: Rob Herring <[email protected]>

2 files changed, 23 insertions, 2 deletions

diff --git a/src/gallium/drivers/panfrost/pan_bo_cache.c b/src/gallium/drivers/panfrost/pan_bo_cache.c
index 7378d0a8abe..9dd6b694b72 100644
--- a/src/gallium/drivers/panfrost/pan_bo_cache.c
+++ b/src/gallium/drivers/panfrost/pan_bo_cache.c
@@ -23,6 +23,8 @@
  * Authors (Collabora):
  *   Alyssa Rosenzweig <[email protected]>
  */
+#include <xf86drm.h>
+#include "drm-uapi/panfrost_drm.h"
 
 #include "pan_screen.h"
 #include "util/u_math.h"
@@ -88,9 +90,21 @@ panfrost_bo_cache_fetch(
         list_for_each_entry_safe(struct panfrost_bo, entry, bucket, link) {
                 if (entry->size >= size &&
                     entry->flags == flags) {
+                        int ret;
+                        struct drm_panfrost_madvise madv;
+
                         /* This one works, splice it out of the cache */
                         list_del(&entry->link);
 
+                        madv.handle = entry->gem_handle;
+                        madv.madv = PANFROST_MADV_WILLNEED;
+                        madv.retained = 0;
+
+                        ret = drmIoctl(screen->fd, DRM_IOCTL_PANFROST_MADVISE, &madv);
+                        if (!ret && !madv.retained) {
+                                panfrost_drm_release_bo(screen, entry, false);
+                                continue;
+                        }
                         /* Let's go! */
                         return entry;
                 }
@@ -109,6 +123,13 @@ panfrost_bo_cache_put(
                 struct panfrost_bo *bo)
 {
         struct list_head *bucket = pan_bucket(screen, bo->size);
+        struct drm_panfrost_madvise madv;
+
+        madv.handle = bo->gem_handle;
+        madv.madv = PANFROST_MADV_DONTNEED;
+	madv.retained = 0;
+
+        drmIoctl(screen->fd, DRM_IOCTL_PANFROST_MADVISE, &madv);
 
         /* Add us to the bucket */
         list_addtail(&bo->link, bucket);
diff --git a/src/gallium/drivers/panfrost/pan_drm.c b/src/gallium/drivers/panfrost/pan_drm.c
index 36a6b975680..28a4287202b 100644
--- a/src/gallium/drivers/panfrost/pan_drm.c
+++ b/src/gallium/drivers/panfrost/pan_drm.c
@@ -163,6 +163,8 @@ panfrost_drm_release_bo(struct panfrost_screen *screen, struct panfrost_bo *bo,
         /* Rather than freeing the BO now, we'll cache the BO for later
          * allocations if we're allowed to */
 
+        panfrost_drm_munmap_bo(screen, bo);
+
         if (cacheable) {
                 bool cached = panfrost_bo_cache_put(screen, bo);
 
@@ -172,8 +174,6 @@ panfrost_drm_release_bo(struct panfrost_screen *screen, struct panfrost_bo *bo,
 
         /* Otherwise, if the BO wasn't cached, we'll legitimately free the BO */
 
-        panfrost_drm_munmap_bo(screen, bo);
-
         ret = drmIoctl(screen->fd, DRM_IOCTL_GEM_CLOSE, &gem_close);
         if (ret) {
                 fprintf(stderr, "DRM_IOCTL_GEM_CLOSE failed: %m\n");