brians

That is some good investigating

PaoloGiandoso
I just checked and it it seems non uniform string primvars are not supported in 20.5 Karma XPU yet unfortunately.

Unfortunately, we have not had a chance to get this feature into H20.5 as we hoped. But it is a high priority for us, so we're at least aiming for the next release.

PaoloGiandoso
About this last method, you previously wrote:

brians
Yes, XPU currently pre-loads all the texture data.
So in this case it will pre-load ALL UDIMs, whether they're needed or not

Does it mean this method won't be very efficient, correct?

H19.5 had to pre-load everything (so was not efficient at all with UDIMS).
Since H20 we have had on-demand loading, meaning UDIMS are efficient now

wanglifu
In my test,the variance mode is slower than uniform mode.Why?

How many pixel samples were you rendering with?
variance oracle only really benefits final-frame rendering when large sample counts are used, otherwise the overheads associated with it will probably outweigh the benefits.

wanglifu
And we can't download the daily builds?

Not yet, they'll be ready in approx 1-2 weeks

GCharb
I did a few more render tests with XPU ray-trace

What driver are you on?
If you're on a 555+ driver, then you'll get the NVidia "Shader Execution Reordering" feature (new hardware in the ADA generation of GPUs)