#+title: 7d.nz
#+author: Phil. Estival
* • [2015-05-29 ven.] BaraCUDA :cuda:graphics:
with one "r" or 2.
A proof of concept of a kernel composition
utility, meant to break down the writing of cuda
kernel into smaller pieces and examinate the
rendering result of the combinations in realtime.
./img/BaraCuda.jpg
It's written with QT5 and tested with cuda v4 to v7.
https://github.com/flintforge/baracuda/
** GLSL sauce
A GLSL wrapper is included : with a few modifications, a
GLSL code will compile. Not all, as the wrapper is fairly
incomplete and don't expect performances with it : this
does not generate machine code, but add extra structures,
for the standard glsl functions, swizzles operations and
vectors association/composition to work.
** Build
$ qmake && make
note that if you qmake -project, this will overwrite baracuda.pro
** cuda setup
Check the hardware
lspci -v | grep -i nvidia
If your card is registred as a 3D controller,
you'll need either to run bumblebee,
or turn the GPU as primary device in your BIOS.
check the number id and go to supportedchips
For debian : https://wiki.debian.org/NvidiaGraphicsDrivers
Bumblebee project page : https://wiki.archlinux.org/index.php/bumblebee
For a fresh start on debian :
purge anything related to nvidia and cuda :
apt-get purge nvidia-* cuda-*
install nvidia-driver through the jessie backport :
apt-get install -t jessie-backports bumblebee-nvidia
Inspect any errors by digging into /var/log/Xorg.8.log and kern.log
*** gcc setup
take note that gcc-4.7 and up aren't supported with cuda6
you'll have to install gcc-4.6 g++-4.6 (or 4.4 with cuda5)
*** troubleshoot
CUDA_ERROR_NO_DEVICE (no CUDA-capable devices were detected)
cuInit returned 100
either you're back to start or you forgot to run baracuda
with optirun baracuda
If running the rendering in a virtual framebuffer and that is the case
with optirun -- libqxcb will crash when dragging an item from the
list to composer. For now, the workaround is to add the item when
it's clicked
CUDA_ERROR_INVALID_CONTEXT
This most frequently indicates that there is no context bound to the current thread.
his can also be returned if the context passed to an API call is not a valid handle
(such as a context that has had cuCtxDestroy() invoked on it).
This can happen if you mix different API versions too (i.e. 3010
context with 3020 API calls). See cuCtxGetApiVersion() for more
details.
** How did it started?
Some idiot at the lab wanted to push further their Java
code (they had a publication in Nature Method about
that), but they were unable to figure out what should
be done about large data acquisition, archival and
sharing. All the project manager could do was getting
all red and yell : "we are doing EJB here!". The
glassfish server was consuming 2GB of RAM and leaking
for who knows what (infinispan maybe?), and some memory
was left for an hungry Eclipse. He still wanted to
use that poor and aging ImageJ so bad... later the
lab turned to Omero. The race was long over.
Digital Image Processing by W. Burger and M.J. Burge,
Springer Ed. is in my library. It's not bad, and goes
well along that software, because it's old. Too bad for
them, because in a matter of 18 months and free hands I
would have made, with love, something useful and
ambitious.
BaraCUDA was the alternative project I coded to keep my
sanity during that contract.
** What to do next ?
If you're in need of a QT+CUDA setup, that's a
start. Programs streams linked through pointers
with hooks in between and on-the-fly compilation
can provide great productive setup with quick
code/eval/debug loops.
Coders like to program shaders because the result
gets vizualised in realtime. To put it like Bret
Victor does: it's about immediate connection.
You can also get into similar configuration with
plain C++, instead of inserting a scripting
language like Lua.
I moved to PureData since then, and never lost the
idea that some day, I would do something inspired
by this and by Gem.