If the device is in runtime suspend, resuming takes time and reduces our
powersaving. If this was for a small write into an object, that resume
will take longer than any savings in using the indirect GGTT access to
avoid the cpu cache.
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/i915_gem.c | 21 ++++++++++++++++++---
1 file changed, 18 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 93dfa793975a..8940a6873ca5 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1229,7 +1229,21 @@ i915_gem_gtt_pwrite_fast(struct drm_i915_gem_object *obj,
if (ret)
return ret;
- intel_runtime_pm_get(i915);
+ if (i915_gem_object_has_struct_page(obj)) {
+ /* Avoid waking the device up if we can fallback, as
+ * waking/resuming is very slow (10-100 ms depending
+ * on PCI sleeps and our own resume time). This easily
+ * dwarfs any performance advantage from using the
+ * cache bypass of indirect GGTT access.
+ */
+ if (!intel_runtime_pm_get_if_in_use(i915)) {
+ ret = -EFAULT;
+ goto out_unlock;
+ }
+ } else {
+ intel_runtime_pm_get(i915);
+ }
+
vma = i915_gem_object_ggtt_pin(obj, NULL, 0, 0,
PIN_MAPPABLE | PIN_NONBLOCK);
if (!IS_ERR(vma)) {
@@ -1244,7 +1258,7 @@ i915_gem_gtt_pwrite_fast(struct drm_i915_gem_object *obj,
if (IS_ERR(vma)) {
ret = insert_mappable_node(ggtt, &node, PAGE_SIZE);
if (ret)
- goto out_unlock;
+ goto out_rpm;
GEM_BUG_ON(!node.allocated);
}
@@ -1307,8 +1321,9 @@ i915_gem_gtt_pwrite_fast(struct drm_i915_gem_object *obj,
} else {
i915_vma_unpin(vma);
}
-out_unlock:
+out_rpm:
intel_runtime_pm_put(i915);
+out_unlock:
mutex_unlock(&i915->drm.struct_mutex);
return ret;
}
--
2.14.1
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