radeonsi: implement mechanism for IBs without partial flushes at the end (v6)

(This patch doesn't enable the behavior. It will be enabled in a later
commit.)

Draw calls from multiple IBs can be executed in parallel.

v2: do emit partial flushes on SI
v3: invalidate all shader caches at the beginning of IBs
v4: don't call si_emit_cache_flush in si_flush_gfx_cs if not needed,
    only do this for flushes invoked internally
v5: empty IBs should wait for idle if the flush requires it
v6: split the commit

If we artificially limit the number of draw calls per IB to 5, we'll get
a lot more IBs, leading to a lot more partial flushes. Let's see how
the removal of partial flushes changes GPU utilization in that scenario:

With partial flushes (time busy):
    CP: 99%
    SPI: 86%
    CB: 73:

Without partial flushes (time busy):
    CP: 99%
    SPI: 93%
    CB: 81%

Tested-by: Benedikt Schemmer <[email protected]>
Reviewed-by: Nicolai Hähnle <[email protected]>

1 files changed, 7 insertions, 0 deletions

diff --git a/src/gallium/drivers/radeon/radeon_winsys.h b/src/gallium/drivers/radeon/radeon_winsys.h
index 157b2e40550..fae4fb7a95d 100644
--- a/src/gallium/drivers/radeon/radeon_winsys.h
+++ b/src/gallium/drivers/radeon/radeon_winsys.h
@@ -28,6 +28,13 @@
 
 /* The public winsys interface header for the radeon driver. */
 
+/* Whether the next IB can start immediately and not wait for draws and
+ * dispatches from the current IB to finish. */
+#define RADEON_FLUSH_START_NEXT_GFX_IB_NOW	(1u << 31)
+
+#define RADEON_FLUSH_ASYNC_START_NEXT_GFX_IB_NOW \
+	(PIPE_FLUSH_ASYNC | RADEON_FLUSH_START_NEXT_GFX_IB_NOW)
+
 #include "pipebuffer/pb_buffer.h"
 
 #include "amd/common/ac_gpu_info.h"