Re: [Mesa-dev] [PATCH 1/7] nvc0: reduce the number of PUSH_SPACE in draw path

[Samuel Pitoiset]

On 11/07/2016 04:32 AM, Ilia Mirkin wrote:

On Wed, Oct 26, 2016 at 4:14 AM, Samuel Pitoiset
<samuel.pitoi...@gmail.com> wrote:

On 10/25/2016 09:49 PM, Ilia Mirkin wrote:

What if instance_count = 1M? (It can happen.)

We allocate a giant space in the pushbuf in one shot. Well, anyways this is
not the optimization of the year, so I can drop it. :-)

There are limits to pushbuf sizes. Either drop it, or batch the
instance draws. There's really very limited advantage to doing it this
way though, since PUSH_SPACE is a no-op unless the pushbuf is full.

Yes, it's really minor, I will discard it.

On Tue, Oct 25, 2016 at 3:41 PM, Samuel Pitoiset
<samuel.pitoi...@gmail.com> wrote:

This might help CPU-bounds applications but should not have
any real effects for GPU-bounds ones.

Signed-off-by: Samuel Pitoiset <samuel.pitoi...@gmail.com>
---
 src/gallium/drivers/nouveau/nvc0/nvc0_vbo.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/src/gallium/drivers/nouveau/nvc0/nvc0_vbo.c
b/src/gallium/drivers/nouveau/nvc0/nvc0_vbo.c
index 69ca091..bc4ab9e 100644
--- a/src/gallium/drivers/nouveau/nvc0/nvc0_vbo.c
+++ b/src/gallium/drivers/nouveau/nvc0/nvc0_vbo.c
@@ -598,8 +598,8 @@ nvc0_draw_arrays(struct nvc0_context *nvc0,

    prim = nvc0_prim_gl(mode);

+   PUSH_SPACE(push, 6 * instance_count);
    while (instance_count--) {
-      PUSH_SPACE(push, 6);
       BEGIN_NVC0(push, NVC0_3D(VERTEX_BEGIN_GL), 1);
       PUSH_DATA (push, prim);
       BEGIN_NVC0(push, NVC0_3D(VERTEX_BUFFER_FIRST), 2);
@@ -730,10 +730,9 @@ nvc0_draw_elements(struct nvc0_context *nvc0, bool
shorten,
    }

    if (nvc0->idxbuf.buffer) {
-      PUSH_SPACE(push, 1);
+      PUSH_SPACE(push, 1 + 7 * instance_count);
       IMMED_NVC0(push, NVC0_3D(VERTEX_BEGIN_GL), prim);
       do {
-         PUSH_SPACE(push, 7);
          BEGIN_NVC0(push, NVC0_3D(INDEX_BATCH_FIRST), 2);
          PUSH_DATA (push, start);
          PUSH_DATA (push, count);
@@ -747,8 +746,8 @@ nvc0_draw_elements(struct nvc0_context *nvc0, bool
shorten,
    } else {
       const void *data = nvc0->idxbuf.user_buffer;

+      PUSH_SPACE(push, 3 * instance_count);
       while (instance_count--) {
-         PUSH_SPACE(push, 2);
          BEGIN_NVC0(push, NVC0_3D(VERTEX_BEGIN_GL), 1);
          PUSH_DATA (push, prim);
          switch (index_size) {
@@ -768,7 +767,6 @@ nvc0_draw_elements(struct nvc0_context *nvc0, bool
shorten,
             assert(0);
             return;
          }
-         PUSH_SPACE(push, 1);
          IMMED_NVC0(push, NVC0_3D(VERTEX_END_GL), 0);

          prim |= NVC0_3D_VERTEX_BEGIN_GL_INSTANCE_NEXT;
--
2.10.1

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--
-Samuel

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