[Mesa-dev] [PATCH 1/2] nvc0: reduce overhead from always marking buffers dirty

[Ilia Mirkin]

We would revalidate buffers when anything was touched at all. Which is
unfortunate, since the state tracker does not use CSO's to reduce the
workload. So instead implement a protocol to ensure that something has
changed before revalidating all the SSBOs.

Signed-off-by: Ilia Mirkin <imirkin at alum.mit.edu>
Cc: "12.0" <mesa-stable at lists.freedesktop.org>
---
 src/gallium/drivers/nouveau/nvc0/nvc0_state.c | 26 ++++++++++++++++++++------
 1 file changed, 20 insertions(+), 6 deletions(-)

diff --git a/src/gallium/drivers/nouveau/nvc0/nvc0_state.c b/src/gallium/drivers/nouveau/nvc0/nvc0_state.c
index e437a64..6cdc007 100644
--- a/src/gallium/drivers/nouveau/nvc0/nvc0_state.c
+++ b/src/gallium/drivers/nouveau/nvc0/nvc0_state.c
@@ -1287,29 +1287,41 @@ nvc0_set_shader_images(struct pipe_context *pipe, unsigned shader,
       nvc0_context(pipe)->dirty_3d |= NVC0_NEW_3D_SURFACES;
 }
 
-static void
+static bool
 nvc0_bind_buffers_range(struct nvc0_context *nvc0, const unsigned t,
                          unsigned start, unsigned nr,
                          struct pipe_shader_buffer *pbuffers)
 {
    const unsigned end = start + nr;
-   const unsigned mask = ((1 << nr) - 1) << start;
+   unsigned mask = 0;
    unsigned i;
 
    assert(t < 6);
 
    if (pbuffers) {
       for (i = start; i < end; ++i) {
+         struct pipe_shader_buffer *buf = &nvc0->buffers[t][i];
          const unsigned p = i - start;
+         if (buf->buffer == pbuffers[p].buffer &&
+             buf->buffer_offset == pbuffers[p].buffer_offset &&
+             buf->buffer_size == pbuffers[p].buffer_size)
+            continue;
+
+         mask |= (1 << i);
          if (pbuffers[p].buffer)
             nvc0->buffers_valid[t] |= (1 << i);
          else
             nvc0->buffers_valid[t] &= ~(1 << i);
-         nvc0->buffers[t][i].buffer_offset = pbuffers[p].buffer_offset;
-         nvc0->buffers[t][i].buffer_size = pbuffers[p].buffer_size;
-         pipe_resource_reference(&nvc0->buffers[t][i].buffer, pbuffers[p].buffer);
+         buf->buffer_offset = pbuffers[p].buffer_offset;
+         buf->buffer_size = pbuffers[p].buffer_size;
+         pipe_resource_reference(&buf->buffer, pbuffers[p].buffer);
       }
+      if (!mask)
+         return false;
    } else {
+      mask = ((1 << nr) - 1) << start;
+      if (!(nvc0->buffers_valid[t] & mask))
+         return false;
       for (i = start; i < end; ++i)
          pipe_resource_reference(&nvc0->buffers[t][i].buffer, NULL);
       nvc0->buffers_valid[t] &= ~mask;
@@ -1321,6 +1333,7 @@ nvc0_bind_buffers_range(struct nvc0_context *nvc0, const unsigned t,
    else
       nouveau_bufctx_reset(nvc0->bufctx_3d, NVC0_BIND_3D_BUF);
 
+   return true;
 }
 
 static void
@@ -1330,7 +1343,8 @@ nvc0_set_shader_buffers(struct pipe_context *pipe,
                         struct pipe_shader_buffer *buffers)
 {
    const unsigned s = nvc0_shader_stage(shader);
-   nvc0_bind_buffers_range(nvc0_context(pipe), s, start, nr, buffers);
+   if (!nvc0_bind_buffers_range(nvc0_context(pipe), s, start, nr, buffers))
+      return;
 
    if (s == 5)
       nvc0_context(pipe)->dirty_cp |= NVC0_NEW_CP_BUFFERS;
-- 
2.7.3