drm/i915: Wait for the GPU whilst shrinking, if truly desperate.
By idling the GPU and discarding everything we can when under extreme
memory pressure, the number of OOM-killer events is dramatically
reduced. For instance, this makes it possible to run
firefox-planet-gnome.trace again on my swapless 512MiB i915.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Eric Anholt <eric@anholt.net>
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 47c46ed..3471dec 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -5066,6 +5066,20 @@
}
static int
+i915_gpu_is_active(struct drm_device *dev)
+{
+ drm_i915_private_t *dev_priv = dev->dev_private;
+ int lists_empty;
+
+ spin_lock(&dev_priv->mm.active_list_lock);
+ lists_empty = list_empty(&dev_priv->mm.flushing_list) &&
+ list_empty(&dev_priv->mm.active_list);
+ spin_unlock(&dev_priv->mm.active_list_lock);
+
+ return !lists_empty;
+}
+
+static int
i915_gem_shrink(int nr_to_scan, gfp_t gfp_mask)
{
drm_i915_private_t *dev_priv, *next_dev;
@@ -5094,6 +5108,7 @@
spin_lock(&shrink_list_lock);
+rescan:
/* first scan for clean buffers */
list_for_each_entry_safe(dev_priv, next_dev,
&shrink_list, mm.shrink_list) {
@@ -5151,6 +5166,36 @@
would_deadlock = 0;
}
+ if (nr_to_scan) {
+ int active = 0;
+
+ /*
+ * We are desperate for pages, so as a last resort, wait
+ * for the GPU to finish and discard whatever we can.
+ * This has a dramatic impact to reduce the number of
+ * OOM-killer events whilst running the GPU aggressively.
+ */
+ list_for_each_entry(dev_priv, &shrink_list, mm.shrink_list) {
+ struct drm_device *dev = dev_priv->dev;
+
+ if (!mutex_trylock(&dev->struct_mutex))
+ continue;
+
+ spin_unlock(&shrink_list_lock);
+
+ if (i915_gpu_is_active(dev)) {
+ i915_gpu_idle(dev);
+ active++;
+ }
+
+ spin_lock(&shrink_list_lock);
+ mutex_unlock(&dev->struct_mutex);
+ }
+
+ if (active)
+ goto rescan;
+ }
+
spin_unlock(&shrink_list_lock);
if (would_deadlock)