[Bf-committers] massive cuda speed improvements with Cuda 5.0/5.5

[Dalai Felinto]

Hi Jurgen,

How does this times compare between CUDA 5.0 and 5.5?
(is this a speedup from 5.5 but a slowdown in relation with 5.0? or
it's an overall speed up ?)

--
Dalai

2013/6/3 Jürgen Herrmann <shadowrom at me.com>:
> Hi there,
>
>
>
> I did some tests with cuda 5.0 and 5.5 today and changed the nvcc
> optimization flags for cycles_kernel_cuda.
>
>
>
> I found out the following:
>
>
>
> -          “--opencc-options “ is deprecated for sm_20 and up and should be
> removed from compiler options
>
> -          Stating “-O3” and “—use_fast_math” as nvcc options brings massive
> speedup on my system (more below)
>
> -          We shouldn’t complain about new cuda toolsets that are slow, we
> should find a solution as we can’t use old software forever…
>
>
>
> To the speedups:
>
>
>
> Example 1:
>
> system: i7-3820 @ 3.60GHz, GeForce GTK 660
>
>
>
> Blender (cycles_cuda_kernel) compiled with standard settings:
>
> Mike_pan file took 02:06.60 to render
>
>
>
> Blender (cycles_cuda_kernel) compiled with –O3 –use-fast-math:
>
> Mike_pan took 01:39:93
>
>
>
> There is no optical difference in the render results:
>
>
>
> Image1: http://www.pasteall.org/pic/52757
>
> Image2: http://www.pasteall.org/pic/52758
>
>
>
> I bet there’s more potential in there.
>
>
>
> /Jürgen
>
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