[PATCH vkd3d 2/4] vkd3d: Skip redundant descriptor copies.
Conor McCarthy
cmccarthy at codeweavers.com
Mon Dec 6 23:07:16 CST 2021
Greatly improves performance in Control.
Based on a vkd3d-proton patch by Philip Rebohle.
Signed-off-by: Conor McCarthy <cmccarthy at codeweavers.com>
---
libs/vkd3d/resource.c | 22 +++++++++++++++++++++-
1 file changed, 21 insertions(+), 1 deletion(-)
diff --git a/libs/vkd3d/resource.c b/libs/vkd3d/resource.c
index 19912231..d7888f2f 100644
--- a/libs/vkd3d/resource.c
+++ b/libs/vkd3d/resource.c
@@ -2159,7 +2159,27 @@ void d3d12_desc_copy(struct d3d12_desc *dst, const struct d3d12_desc *src,
assert(dst != src);
/* Shadow of the Tomb Raider and possibly other titles sometimes destroy
- * and rewrite a descriptor in another thread while it is being copied. */
+ * and rewrite a descriptor in another thread while it is being copied.
+ * We don't need to lock either descriptor for the update check. The purpose
+ * of locking descriptors is not to make descriptor writes thread safe,
+ * but only to prevent use-after-free of the vkd3d_view caused by a race
+ * condition in the calling app. It's not important if the update check
+ * falls out of date as it's their race condition, not ours. */
+ if (dst->magic == src->magic)
+ {
+ if (dst->magic & VKD3D_DESCRIPTOR_MAGIC_HAS_VIEW)
+ {
+ if (dst->u.view == src->u.view)
+ return;
+ }
+ else if (dst->u.vk_cbv_info.buffer == src->u.vk_cbv_info.buffer
+ && dst->u.vk_cbv_info.offset == src->u.vk_cbv_info.offset
+ && dst->u.vk_cbv_info.range == src->u.vk_cbv_info.range)
+ {
+ return;
+ }
+ }
+
mutex = d3d12_device_get_descriptor_mutex(device, src);
pthread_mutex_lock(mutex);
--
2.33.0
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