[Bf-cycles] still memory problem with cuLaunch on GTX780Ti 3GB with empty scene

Stefan Werner swerner at smithmicro.com
Tue Sep 15 22:33:01 CEST 2015

Where exactly does that memory requirement come from? Is it the
ShaderData bssrdf_sd[BSSRDF_MAX_HITS];
Array, which I believe is pre-allocated per thread in CUDA local memory, or are there any other areas that contribute significantly to memory usage? From my superficial studying of the code, I was wondering if it was possible to only have ShaderData struct in memory at a time and have subsurface_scatter_multi_step() fill out an array of Intersections instead of ShaderDatas? One would have to move the BSSRDF evaluation to kernel_branched_path_subsurface_scatter() / kernel_path_subsurface_scatter() then instead. It may be that I’m overlooking something though.


From: <bf-cycles-bounces at blender.org<mailto:bf-cycles-bounces at blender.org>> on behalf of Thomas Dinges
Reply-To: Discussion list to assist Cycles render engine developers
Date: Tuesday, September 15, 2015 at 11:56 AM
To: "bf-cycles at blender.org<mailto:bf-cycles at blender.org>"
Subject: Re: [Bf-cycles] still memory problem with cuLaunch on GTX780Ti 3GB with empty scene

This is pretty much a known issue, since day 1 of the experimental kernel. We added the experimental kernel for features such as SSS, which are the cause of the memory peak (or rather SSS enabled as part of our mega kernel).
The only real solution here will be the CUDA split kernel. That split might still happen later this year, it's on our todo list.

Until then, as Brecht said, use it at your own risk.

Am 15.09.2015 um 19:54 schrieb Piotr Arlukowicz:
Thank you Brecht, I understand this and that's OK with memory, but... still 1.5GB is not enough even for empty scene... ? Come on! :)
I was so desperate that I started to look which GTX should I buy. Surely 980Ti with 6GiB is a great graphics card, but WILL it work?

Few months ago Cycles worked in experimental mode just very well and as I don't require it to be bulletproof, this memory lag just kicks me out :( Sorry for sharing personal mood on the list. I hope somebody can advice what to do. Because I don't know if 6GB will be enough, and then there is also Titan with 12GB...


​ Arlukowicz, BFCT​

Blender Network:<https://www.blendernetwork.org/piotr-arlukowicz>https://www.blendernetwork.org/piotr-arlukowicz
Polski Kurs Blendera:<http://polskikursblendera.pl>http://polskikursblendera.pl

2015-09-15 18:08 GMT+02:00 Brecht Van Lommel <brechtvanlommel at pandora.be<mailto:brechtvanlommel at pandora.be>>:
Experimental mode uses significantly more memory. I don't know if this
is more than expected at the moment, but it wouldn't surprise me.

This memory usage is one of the main reasons it's called experimental
mode, if all the features there worked well they would not be called
experimental. I know a lot of users enable this but it's really at
your own risk.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.blender.org/pipermail/bf-cycles/attachments/20150915/4e4c36f4/attachment.htm 

More information about the Bf-cycles mailing list