[Mesa-dev] [PATCH 1/2] gallium: add PIPE_FLUSH_DEFERRED

[Marek Olšák]

From: Marek Olšák <marek.olsak at amd.com>

There are 2 uses:
- Asynchronous flushing for multithreaded drivers.
- Return a fence without flushing (mid-command-buffer fence). The driver
  can defer flushing until fence_finish is called.

This is required to make Bioshock Infinite faster, which creates
1000 fences (flushes) per frame.
---
 src/gallium/docs/source/context.rst    | 5 +++++
 src/gallium/include/pipe/p_defines.h   | 3 ++-
 src/mesa/state_tracker/st_cb_syncobj.c | 2 +-
 3 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/src/gallium/docs/source/context.rst b/src/gallium/docs/source/context.rst
index 05c6f11..2f803ac 100644
--- a/src/gallium/docs/source/context.rst
+++ b/src/gallium/docs/source/context.rst
@@ -463,6 +463,11 @@ Flushing
 
 ``flush``
 
+PIPE_FLUSH_END_OF_FRAME: Whether the flush marks the end of frame.
+PIPE_FLUSH_DEFERRED: It is not required to flush right away, but it is required
+to return a valid fence.
+
+
 
 ``flush_resource``
 
diff --git a/src/gallium/include/pipe/p_defines.h b/src/gallium/include/pipe/p_defines.h
index 62fa673..a2f5193 100644
--- a/src/gallium/include/pipe/p_defines.h
+++ b/src/gallium/include/pipe/p_defines.h
@@ -348,7 +348,8 @@ enum pipe_transfer_usage
  */
 enum pipe_flush_flags
 {
-   PIPE_FLUSH_END_OF_FRAME = (1 << 0)
+   PIPE_FLUSH_END_OF_FRAME = (1 << 0),
+   PIPE_FLUSH_DEFERRED = (1 << 1),
 };
 
 /**
diff --git a/src/mesa/state_tracker/st_cb_syncobj.c b/src/mesa/state_tracker/st_cb_syncobj.c
index ec2687f..69f2a28 100644
--- a/src/mesa/state_tracker/st_cb_syncobj.c
+++ b/src/mesa/state_tracker/st_cb_syncobj.c
@@ -73,7 +73,7 @@ static void st_fence_sync(struct gl_context *ctx, struct gl_sync_object *obj,
    assert(condition == GL_SYNC_GPU_COMMANDS_COMPLETE && flags == 0);
    assert(so->fence == NULL);
 
-   pipe->flush(pipe, &so->fence, 0);
+   pipe->flush(pipe, &so->fence, PIPE_FLUSH_DEFERRED);
 }
 
 static void st_check_sync(struct gl_context *ctx, struct gl_sync_object *obj)
-- 
2.7.4