VRay Diagnostics

[Macker]

Hey guys,

I was wondering if it would be possible to have some kind of VRay Diagnostics window that opens every time you render (kind of like the vray messsages window).

It would be useful to see what things in the scene are using the most memory, be it textures, geometry or displacement. It would also be useful to see what things VRay is caching to hard disk.

The reason I thought of this is that I've got a scene that I've left to batch render over the weekend and I've come in and it's still going - frames are taking 17 hours, and that's with two dual xeon render nodes working on them too. All of them are at ~3% CPU usage, but 100% disk and memory usage - so presumably things are being cached? I need a way of finding out what is causing the problems to be able to tackle it (my suspicion is displacement).

[vlado]

We are working on better memory statistics, so hopefully it will get there soon. Generally it's either geometry or textures, or in the case of large images - the frame buffer. Displacement/subdivision surfaces could also be a problem for large resolution images and low "edge length" parameters.

Best regards,
Vlado

[Macker]

Yeah, I think it's probably a combination of it being high res (6000 pixels) and 3 pixel edge length, which was of course fine on lower resolution renders.

[Edit] Would having an SSD speed up this kind of caching noticeably?

[vlado]

[Edit] Would having an SSD speed up this kind of caching noticeably?

Maybe a bit, but still a lot slower than if it wasn't necessary.

Best regards,
Vlado

[Macker]

what if it were a PCIe SSD? We have a brand new one in one of our servers that isn't being used.

[vlado]

what if it were a PCIe SSD? We have a brand new one in one of our servers that isn't being used.

I haven't tried that myself, so I wouldn't know. It will probably be faster, but by how much - I have no idea. I'll see if I can get such a set up here.

Best regards,
Vlado

[Macker]

Awesome. When you get hold of these things, do you buy them or rent them? Surely it must be expensive to keep buying things in to test setups?

[vlado]

Awesome. When you get hold of these things, do you buy them or rent them? Surely it must be expensive to keep buying things in to test setups?

I think we usually end up buying them; unfortunately very few people here need such hardware so most resellers are only willing to put in the order if we pay for it.

Best regards,
Vlado

[Macker]

You must have some serious gear at your end then! Most powerful workstation?

[vlado]

You must have some serious gear at your end then! Most powerful workstation?

No, not really; my own workstation is a single i7-4771 at 3 GHz. More powerful machines make a lot of noise so we keep them in the server room and share them with remote desktop when needed for testing.

Best regards,
Vlado

[^Lele^]

All of them are at ~3% CPU usage, but 100% disk and memory usage - so presumably things are being cached? I need a way of finding out what is causing the problems to be able to tackle it (my suspicion is displacement).

You're likely swapping to disk from out of RAM.
However, you do have options for this situation which at least will save you from disk swapping:
The Dynamic memory limit and the texture cache limit (for tiled EXRs it works best).
The former, in the settings tab, determines how much dynamic geometry (displacement, fur, and so on) can stay in ram before being swapped out (not to disk!) when not needed, the latter does the same for (tiled) textures (you can find it on the vrayHDRI loader, or on the nightlies in the advanced system tab).
The theory goes that you ought to set the two values to something fitting your ram budget (all the "static" geo will have to be loaded, and perhaps you'll also have a VFB taking up some ram, perhaps not).
So for example, if your basic geo and acceleration structures and VFB took 8gb altogether, and your slave had 16, then you'd have another 8000 MB of ram to share between dyn mem limit and texture cache, so you could set both to, say, 4000MB.

When set up as such, only the stuff which can fit in memory will be loaded, and when the ram pool is filled to the brim, old data is discarded to make room for the new one, without the Disks getting a whiff of activity due to the swapping for out of ram.
If you're REALLY ram strapped, for whatever reason, consider also rendering to tiled, in bufferless mode: big resolution and many REs WILL eat up ram for breakfast.

[Macker]

So the render finished a couple of hours ago(!) and it is still saying "clearing ray server" in the log. Should I keep waiting, or force it to close? It'd be a real shame to lose the render.

[vlado]

So the render finished a couple of hours ago(!) and it is still saying "clearing ray server" in the log. Should I keep waiting, or force it to close? It'd be a real shame to lose the render.

Wait it out, it will finish. But based on that, it's probably the displacement.

Best regards,
Vlado

[anthonyh]

always to each their own. personally i wish the information box was turned off as default as i have to turn it off manually every time. i`m sure everyone likes their own setup and that`s part of mine.