On 03.07.2017 18:33, Samuel Pitoiset wrote:
On 07/03/2017 06:16 PM, Samuel Pitoiset wrote:
On 07/03/2017 06:09 PM, Nicolai Hähnle wrote:
On 03.07.2017 18:03, Nicolai Hähnle wrote:
On 29.06.2017 21:59, Samuel Pitoiset wrote:
Only emit partial flushes when the underlying shader stages
are using bindless samplers or images.
This gets rid of 4% of partial flushes in the DOW3 benchmark.
Do those flushes still trigger during play?
I'd think it should be possible to eliminate these partial flushes
entirely. The logic is that you only ever need the wait in the first
place when you're overriding a previously used descriptor.
So what you could do is add a counter (per context, I think?) which
is incremented whenever a flush happens, and then release
descriptors lazily based on that.
Alternatively (maybe easier, not sure): all shaders are guaranteed
to have finished when the fence of a submit fires, so use that as
the guard for lazily releasing descriptors.
Looking at the other patch, it seems the flushes are triggered for
descriptor changes for buffer invalidations? In that case, forget
what I wrote.
Yes, most of them are for buffer invalidations.
One thing we can do though is to scan all shaders in order to know if
they use bindless texture buffers. Maybe this can help for removing more
partial flushes, what do you think?
Having the descriptors is proof that *some* shaders use texture buffers.
If it's only a small minority of shaders, then that might help. I don't
know how DOW3 uses it, so it's hard to say.
Also, I think I have to retract my R-b for this patch. There's an issue
that occurred to me unfortunately (or fortunately, depending on how you
look at it). Consider a sequence like:
1. draw with bindless
2. draw without bindless
3. buffer invalidation that triggers descriptor upload
4. draw without bindless
At step 3, we would no longer do a shader partial flush with this patch.
However, shaders from the first draw might still be running!
I'm not sure if we can fix that. Basically, whenever we started a draw
with bindless since the last (implied) gfx shader flush, we need to
issue a flush before updating descriptors. So you could track that with
a si_context bit that gets set when any shaders use bindless, and
cleared with an (implied) gfx shader flush. But I don't know how much
that really helps, and I don't think there's anything else we can do.
Even crazy schemes like manually counting context rolls wouldn't help,
because we can't avoid invalidating the L1K$.
We're entering Vulkan-like territory where we might have to ask Feral to
improve their buffer handling.
Cheers,
Nicolai
Cheers,
Nicolai
Anyway, this patch is a nice first step.
Reviewed-by: Nicolai Hähnle <[email protected]>
Signed-off-by: Samuel Pitoiset <[email protected]>
---
src/gallium/drivers/radeonsi/si_descriptors.c | 18
++++++++++++++++--
1 file changed, 16 insertions(+), 2 deletions(-)
diff --git a/src/gallium/drivers/radeonsi/si_descriptors.c
b/src/gallium/drivers/radeonsi/si_descriptors.c
index 88f7dcee959..7d8b3670887 100644
--- a/src/gallium/drivers/radeonsi/si_descriptors.c
+++ b/src/gallium/drivers/radeonsi/si_descriptors.c
@@ -1934,14 +1934,28 @@ static void
si_upload_bindless_descriptor(struct si_context *sctx,
static void si_upload_bindless_descriptors(struct si_context *sctx)
{
+ unsigned shader_uses_bindless_mask;
+
if (!sctx->bindless_descriptors_dirty)
return;
/* Wait for graphics/compute to be idle before updating the
resident
* descriptors directly in memory, in case the GPU is using
them.
*/
- sctx->b.flags |= SI_CONTEXT_PS_PARTIAL_FLUSH |
- SI_CONTEXT_CS_PARTIAL_FLUSH;
+ sctx->b.flags |= SI_CONTEXT_CS_PARTIAL_FLUSH;
+
+ /* To avoid unnecessary partial flushes, check which shader
stages are
+ * using bindless samplers or images.
+ */
+ shader_uses_bindless_mask =
sctx->shader_uses_bindless_samplers_mask |
+ sctx->shader_uses_bindless_images_mask;
+
+ if (shader_uses_bindless_mask & (1 << PIPE_SHADER_FRAGMENT)) {
+ sctx->b.flags |= SI_CONTEXT_PS_PARTIAL_FLUSH;
+ } else if (shader_uses_bindless_mask) {
+ sctx->b.flags |= SI_CONTEXT_VS_PARTIAL_FLUSH;
+ }
+
si_emit_cache_flush(sctx);
util_dynarray_foreach(&sctx->resident_tex_handles,
--
Lerne, wie die Welt wirklich ist,
Aber vergiss niemals, wie sie sein sollte.
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