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>
Reviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
---
drivers/gpu/drm/i915/i915_gem.c | 23 ++++++++++++++++++++---
1 file changed, 20 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index d699ea3ab80b..026cb52ece0b 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1240,7 +1240,23 @@ 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 (worst-case 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 {
+ /* No backing pages, no fallback, we must force GGTT access */
+ intel_runtime_pm_get(i915);
+ }
+
vma = i915_gem_object_ggtt_pin(obj, NULL, 0, 0,
PIN_MAPPABLE |
PIN_NONFAULT |
@@ -1257,7 +1273,7 @@ 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);
}
@@ -1320,8 +1336,9 @@ 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;
}
--
2.15.0.rc1
_______________________________________________
Intel-gfx mailing list
Intel-gfx@xxxxxxxxxxxxxxxxxxxxx
https://lists.freedesktop.org/mailman/listinfo/intel-gfx
