[PATCH 2/2] drm/i915: Maintain LRU order of inactive objects upon access by CPU

From: Chris Wilson <chris@chris-wilson.co.uk>
To: intel-gfx@lists.freedesktop.org
Subject: [PATCH 2/2] drm/i915: Maintain LRU order of inactive objects upon access by CPU
Date: Thu,  1 Jul 2010 17:53:45 +0100	[thread overview]
Message-ID: <1278003225-937-2-git-send-email-chris@chris-wilson.co.uk> (raw)
In-Reply-To: <1278003225-937-1-git-send-email-chris@chris-wilson.co.uk>

In order to reduce the penalty of fallbacks under memory pressure and to
avoid a potential immediate ping-pong of evicting a mmaped buffer, we
move the object to the tail of the inactive list when a page is freshly
faulted or the object is moved into the CPU domain.

We choose not to protect the CPU objects from casual eviction,
preferring to keep the GPU active for as long as possible.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_gem.c |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 7d20901..c310fbe 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1072,6 +1072,10 @@ i915_gem_set_domain_ioctl(struct drm_device *dev, void *data,
 		ret = i915_gem_object_set_to_cpu_domain(obj, write_domain != 0);
 	}
 
+	/* Maintain LRU order of "inactive" objects */
+	if (ret == 0 && obj_priv->gtt_space && !obj_priv->active)
+		list_move_tail(&obj_priv->list, &dev_priv->mm.inactive_list);
+
 	drm_gem_object_unreference(obj);
 	mutex_unlock(&dev->struct_mutex);
 	return ret;
@@ -1205,6 +1209,9 @@ int i915_gem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 			goto unlock;
 	}
 
+	if (!obj_priv->active)
+		list_move_tail(&obj_priv->list, &dev_priv->mm.inactive_list);
+
 	pfn = ((dev->agp->base + obj_priv->gtt_offset) >> PAGE_SHIFT) +
 		page_offset;
 
-- 
1.7.1
