[Rtk-users] Cuda and RTK

[Fredrik Hellman]

Hi,

Ok, thank you! Although I have no concrete changes in mind already now, I
at least know that the itk cuda common code is maintained via RTK and open
for contributions.

As far as I understand from
https://devblogs.nvidia.com/gpu-pro-tip-cuda-7-streams-simplify-concurrency,
the default stream is always synchronous if the code is not compiled with
the special thread-specific default stream flag.

Yes, it is for tomographic reconstruction, so I use some RTK code, e.g. FDK
reconstruction. But I am writing some of my own filters that should work
together with it, using the itk Cuda Image as image type. So no, I don't
have any special algorithm from RTK in mind..

/ Fredrik

Den tors 9 maj 2019 kl 21:46 skrev Simon Rit <simon.rit at creatis.insa-lyon.fr
>:

> Hi,
> I would definitely be interested in improving RTK! We haven't discussed
> about this earlier and I don't see why the community would not be
> interested in improvements. If you start coding something, my preferences
> would be to have backward compatible code. Feel free to propose some PRs.
> I'm a bit surprised about your comment on streams, I was pretty sure that
> the computation and the data transfer were asynchronous as is. And about
> the memory pool, why not, that sounds interesting, as long as we can still
> allocate as much as before. About the streaming part, if does not
> reallocate if there is no change in memory size I believe.
> Are your developments related to tomographic reconstruction? If yes, is
> there some RTK algorithms for which you expect a significant improvement?
> Thanks for your suggestions,
> Simon
>
> On Thu, May 9, 2019 at 6:08 PM Fredrik Hellman <fredrik.hellman at gmail.com>
> wrote:
>
>> Hi,
>>
>> Thanks Simon! I see.
>>
>> I am writing a CUDA application of which where RTK and ITK will be parts,
>> and I want to know how RTK CUDA cooperates with the CUDA functionality I
>> already have in my application. I have found some behaviors that would be
>> nice to be able to control/change or at least understand the design of:
>>
>> * Context handling. It appears the CUDA context manager keeps track of
>> contexts and also can switch between them, I think I would like to be able
>> to control this on a higher level. I can see situations where multple
>> libraries compete with the control of contexts.
>> * Streams. It would be nice to be able to perform data transfer between
>> CPU/GPU in parallell with computations, but that requires that another
>> stream than the default stream is used, since the default stream is always
>> synchronous.
>> * Memory allocations. When CUDA memory is allocated and deallocated, it
>> implicitly synchronizes all operations on the GPU (
>> https://docs.nvidia.com/cuda/cuda-c-programming-guide/#implicit-synchronization).
>> It would be good if one could either provide allocators/deallocates for a
>> memory pool which doesn't need to issue the actual allocation calls, but
>> get buffers from a pre allocated pool. Or find a a way to disable
>> reallocations (which sometimes can be very frequent in ITK, especially if
>> doing streaming).
>>
>> Are these areas that the community would be interested in too? Has there
>> been any developments or discussions about this earlier?
>>
>> Best regards,
>> Fredrik Hellman
>>
>> On Tue, 30 Apr 2019 at 15:02, Simon Rit <simon.rit at creatis.insa-lyon.fr>
>> wrote:
>>
>>> Hi,
>>> Everything you're saying is correct. This development was co-funded by
>>> the RTK consortium and Kitware and the goal was to transfer it to ITK.
>>> However, this has never occurred and at this stage, it is only maintained
>>> in RTK. Ideally, this could become an independent ITK module.
>>> Is it something you'd like/need?
>>> Cheers,
>>> Simon
>>>
>>> On Tue, Apr 30, 2019 at 2:58 PM Fredrik Hellman <
>>> fredrik.hellman at gmail.com> wrote:
>>>
>>>> Hi all,
>>>>
>>>> I have a question about the the code that deals with cuda within RTK.
>>>>
>>>> RTK uses itk cuda image, the itk data manager, and itk context manager
>>>> (but not itk kernel manager so much?) to handle cuda data. Is this
>>>> maintained as part of RTK or is it maintained somewhere else and only used
>>>> in RTK? Now when RTK becomes closer to ITK, what will happen to that code?
>>>>
>>>> Best regards,
>>>> Fredrik
>>>>
>>> _______________________________________________
>>>> Rtk-users mailing list
>>>> Rtk-users at public.kitware.com
>>>> https://public.kitware.com/mailman/listinfo/rtk-users
>>>>
>>>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://public.kitware.com/pipermail/rtk-users/attachments/20190514/4d9115a7/attachment.html>