Mesa (master): iris: Use MI_COPY_MEM_MEM for tiny resource_copy_region calls.
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Mon Jul 1 21:00:00 UTC 2019
Module: Mesa
Branch: master
Commit: 9b1b9714915c3e3d08582fd1d77f182cdf3e5090
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=9b1b9714915c3e3d08582fd1d77f182cdf3e5090
Author: Kenneth Graunke <kenneth at whitecape.org>
Date: Wed Jun 26 00:05:06 2019 -0700
iris: Use MI_COPY_MEM_MEM for tiny resource_copy_region calls.
If our resource_copy_region size is a small number of DWords, then
instead of firing up BLORP, we can simply use MI_COPY_MEM_MEM (after
a CS stall). We also try and select the optimal batch.
Improves performance in Shadow of Mordor on Low settings at 1920x1080
on Skylake GT4e by 0.689096% +/- 0.473968% (n=4). It tries to copy
4 bytes of data to a buffer which was most recently used as a writable
compute shader SSBO. Previously we were switching from compute to the
render pipeline, then firing up all of blorp_buffer_copy...for 4 bytes.
I arbitrarily decided to support 4/8/12/16 bytes. Jason thinks this
is about the right threshold where it's cheaper to use MI_COPY_MEM_MEM.
---
src/gallium/drivers/iris/iris_blit.c | 27 +++++++++++++++++++++++++++
1 file changed, 27 insertions(+)
diff --git a/src/gallium/drivers/iris/iris_blit.c b/src/gallium/drivers/iris/iris_blit.c
index 6f90910b516..6fa452c68b1 100644
--- a/src/gallium/drivers/iris/iris_blit.c
+++ b/src/gallium/drivers/iris/iris_blit.c
@@ -608,6 +608,19 @@ iris_copy_region(struct blorp_context *blorp,
tex_cache_flush_hack(batch);
}
+static struct iris_batch *
+get_preferred_batch(struct iris_context *ice, struct iris_bo *bo)
+{
+ /* If the compute batch is already using this buffer, we'd prefer to
+ * continue queueing in the compute batch.
+ */
+ if (iris_batch_references(&ice->batches[IRIS_BATCH_COMPUTE], bo))
+ return &ice->batches[IRIS_BATCH_COMPUTE];
+
+ /* Otherwise default to the render batch. */
+ return &ice->batches[IRIS_BATCH_RENDER];
+}
+
/**
* The pipe->resource_copy_region() driver hook.
@@ -627,6 +640,20 @@ iris_resource_copy_region(struct pipe_context *ctx,
struct iris_context *ice = (void *) ctx;
struct iris_batch *batch = &ice->batches[IRIS_BATCH_RENDER];
+ /* Use MI_COPY_MEM_MEM for tiny (<= 16 byte, % 4) buffer copies. */
+ if (src->target == PIPE_BUFFER && dst->target == PIPE_BUFFER &&
+ (src_box->width % 4 == 0) && src_box->width <= 16) {
+ struct iris_bo *dst_bo = iris_resource_bo(dst);
+ batch = get_preferred_batch(ice, dst_bo);
+ iris_batch_maybe_flush(batch, 24 + 5 * (src_box->width / 4));
+ iris_emit_pipe_control_flush(batch,
+ "stall for MI_COPY_MEM_MEM copy_region",
+ PIPE_CONTROL_CS_STALL);
+ ice->vtbl.copy_mem_mem(batch, dst_bo, dstx, iris_resource_bo(src),
+ src_box->x, src_box->width);
+ return;
+ }
+
iris_copy_region(&ice->blorp, batch, dst, dst_level, dstx, dsty, dstz,
src, src_level, src_box);
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