drm/i915: Move the recently scanned objects to the tail after shrinking

During shrinking, we walk over the list of objects searching for
victims. Any that are not removed are put back into the global list.
Currently, they are put back in order (at the front) which means they
will be first to be scanned again. If we instead move them to the rear
of the list, we will scan new potential victims on the next pass and
waste less time rescanning unshrinkable objects. Normally the lists are
kept in rough order to shrinking (with object least frequently used at
the start), by moving just scanned objects to the rear we are
acknowledging that they are still in use.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161101084843.3961-3-chris@chris-wilson.co.uk

diff --git a/drivers/gpu/drm/i915/i915_gem_shrinker.c b/drivers/gpu/drm/i915/i915_gem_shrinker.c
index 9ace5f9f53172dcc447236c2f3d54e4574d873bc..0993afc0e725b75749e06ffee0d2a86641a4b31d 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem_shrinker.c
+++ b/drivers/gpu/drm/i915/i915_gem_shrinker.c
@@ -234,7 +234,7 @@ i915_gem_shrink(struct drm_i915_private *dev_priv,
                                mutex_unlock(&obj->mm.lock);
                        }
                }
-               list_splice(&still_in_list, phase->list);
+               list_splice_tail(&still_in_list, phase->list);
        }
 
        if (flags & I915_SHRINK_BOUND)