Re: [PATCH] drm/ttm: Don't evict BOs outside of the requested placement range

On 09.10.2014 19:22, Alan Swanson wrote:

On 2014-10-09 07:02, Michel Dänzer wrote:

...

From: Michel Dänzer michel.daenzer@amd.com

The radeon driver uses placement range restrictions for several reasons, in particular to make sure BOs in VRAM can be accessed by the CPU, e.g. during a page fault.

Without this change, TTM could evict other BOs while trying to satisfy the requested placement, even if the evicted BOs were outside of the requested placement range. Doing so didn't free up any space in the requested placement range, so the (potentially high) eviction cost was incurred for no benefit.

Nominating for stable because radeon driver changes in 3.17 made this much more noticeable than before.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=84662 Cc: stable@vger.kernel.org Signed-off-by: Michel Dänzer michel.daenzer@amd.com

---

drivers/gpu/drm/ttm/ttm_bo.c | 20 +++++++++++++++++--- 1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c index 8f5cec6..407fa2d 100644 --- a/drivers/gpu/drm/ttm/ttm_bo.c +++ b/drivers/gpu/drm/ttm/ttm_bo.c @@ -709,6 +709,7 @@ out:

static int ttm_mem_evict_first(struct ttm_bo_device *bdev, uint32_t mem_type,

•            const struct ttm_place *place,
             bool interruptible,
             bool no_wait_gpu)
  

{ @@ -720,8 +721,21 @@ static int ttm_mem_evict_first(struct ttm_bo_device *bdev, spin_lock(&glob->lru_lock); list_for_each_entry(bo, &man->lru, lru) { ret = __ttm_bo_reserve(bo, false, true, false, NULL);

•    if (!ret)
  

•    if (!ret) {
  

•        if (place && (place->fpfn || place->lpfn)) {
  

•            /* Don't evict this BO if it's outside of the
  

•             * requested placement range
  

•             */
  

•            if (place->fpfn >= (bo->mem.start + bo->mem.size) ||
  

•                (place->lpfn && place->lpfn <= bo->mem.start)) {
  

•                __ttm_bo_unreserve(bo);
  

•                ret = -EBUSY;
  

•                continue;
  

•            }
  

•        }
  

•        break;
  

•    }
  

  }

  if (ret) {

@@ -782,7 +796,7 @@ static int ttm_bo_mem_force_space(struct ttm_buffer_object *bo, return ret; if (mem->mm_node) break;

•    ret = ttm_mem_evict_first(bdev, mem_type,
  

•    ret = ttm_mem_evict_first(bdev, mem_type, place,
                   interruptible, no_wait_gpu);
     if (unlikely(ret != 0))
         return ret;
  

[...]

I believe you need to "s/place/placement/" over this patch.

The fpfn and lpfn members were moved from struct ttm_placement to a new struct ttm_place in f1217ed09f827e42a49ffa6a5aab672aa6f57a65.

If you mean something else, please elaborate.