I have noticed that there is only one rendertile (Regardless of what set for threads, I have tried fixed and not fixed) and the CPU is being used while set on the GPU is not being used at all. Did anyone have the same experience? why would this happen? all.
n-GPU = n-Render Tile
ie. 2 GPUs > 2 render tiles
n-CPU Thread = n-Render Tile
ie. 1 CPU = 4 core = 8 threads > 8 render tiles
CPU always runs runs cuz it’s making stuff for GPU to process
(with W10 CPU also takes care for all the extra details that Ms. Cortana needs to know & control)
In addition to @burnin’s reply, i suggest using this addon: Auto Tile Size . So basically, when you render with GPU set your tile-sizes bigger (around 256). This addon just configures it automatically according to your resolution.
And check this: 4 Easy Ways to Speed Up Cycles
Hi.
Auto tile size addon does not choose sizes according to resolution or any other parameter when it automatically chooses a value, it simply chooses one size around 256 because that was a suitable size for cards before Maxwell architecture. Actually, there is no way to know what the optimal size will be because it depends on the scene and architecture of the GPU. But starting from Maxwell inclusive, the size that is close to being optimal for the average of the scenes is around 480x270 (512), but not 256.
Anyway, that addon will not be useful in Blender 2.80 because the optimal size for CPU and GPU will be a small size, like 16x16.
Edit:
Maybe I misinterpreted this: “This addon just configures it automatically according to your resolution.”
Yes, it automatically chooses sizes around 256 to make tiles better to fit in resolution of the render. But that does not mean that optimal sizes of tiles depend on the resolution of the render, and it does not mean that for example the addon will automatically choose good sizes for Maxwell and Pascal cards, because the sizes are always around 256.
@krajkoa,
In Blender because how it works for its design, when you render with GPU (CUDA), one CPU thread per GPU is used at 100%, plus another CPU thread randomly in use for other tasks while rendering. So in your case when you render with GPU you will see two CPU threads being used in the system monitor. That does not mean that those CPU threads are being used for rendering, so you’ll see only one tile corresponding for the GPU working while rendering.
I didn’t say addon chooses size (told him to set size around 256 manually) but addon configures proportionally according to your resolution to fit perfectly. Check below gif:
Edit: just saw your edit
I use GTX 1070 and %99 times it’s faster slightly if i choose around 256 and not 512.
Well, some scenes can be close to 256, but that is far from the majority with my GTX 960 where it generally works best with large sizes. And in this other user with GTX 1080 Ti also most of the times are sizes greater than 256:
https://blenderartists.org/t/gtx-1080-ti-various-benchmarks-bmw-classroom-fishy-cat/685785/44
https://blenderartists.org/t/gtx-1080-ti-various-benchmarks-bmw-classroom-fishy-cat/685785/48
Anyway the headaches to configure optimal tiles will end with Blender 2.8 (hopefully)