January 2015 - Boost - lists.boost.org

[compute] Review
by Yiannis Papadopoulos 02 Jan '15

02 Jan '15

Hi, This is my review of Boost.Compute: 1. What is your evaluation of the design? It seems logical to me. It is effectively a wrapper around OpenCL that provides implementations of higher-level algorithms, and allows interoperability with OpenCL and OpenGL. The Boost.Compute name is a bit misleading, as Boost.Compute supports only OpenCL-enabled devices. 2. What is your evaluation of the implementation? There is some code duplication (e.g. type traits) and various other bits and pieces that can be moved to existing Boost components. I think there should be some effort spent towards that. It seems that performance is on par with Thrust. However, there are other libraries out there (e.g Bolt) and multiple devices, so there has to be a more extensive experimental evaluation to say decidedly that it is a good implementation. 3. What is your evaluation of the documentation? Overall, it is pretty good. Given the complexity of the accelerator programming model, a few more elaborate examples in the tutorial would be welcome. 4. What is your evaluation of the potential usefulness of the library? This is difficult to answer. A lot of work has been put in this library and it seems the way to go. The interfaces are clean, the code looks solid and the developer willing. However, there is limited vendor support, there are not enough benchmarks and there are other alternatives that they have both. Given that Boost.Compute is targeted to users that know a thing or two about performance, I don't know how they can be convinced to consider using Boost.Compute against Bolt or Thrust. 5. Did you try to use the library? With what compiler? Did you have any problems? I did using an AMD 7850 on Linux with gcc 4.8. The few examples I tried, compiled and ran fine. 6. How much effort did you put into your evaluation? A glance? A quick reading? In-depth study? I went over the documentation, I glanced over the code and ran a few examples. 7. Are you knowledgeable about the problem domain? I'm in the HPC field. I have extensive experience with MPI, OpenMP, pthreads, and less with TBB, CUDA and OpenCL. 8. Do you think the library should be accepted as a Boost library? This will be a maybe. It is a well-written library with a few minor issues that can be resolved. However, why would someone use Boost.Compute against what is out there? Average users can resort to Bolt or Thrust. Power users will probably always try to hand-tune their OpenCL or CUDA algorithm. How can we test it and prove its performance? Regards, Yiannis

5 7

[compute] Review results
by Antony Polukhin 01 Jan '15

01 Jan '15

Hi all, Extended review period for Boost.Compute library has ended. Here are the review votes for inclusion (+ means include, - means do not include, +/- means conditional include or "probably include, not quite sure"): + Denis Demidov + Sebastian Schaetz + Pavan Yalamanchili - Gruenke,Matt (+ if more backends will be supported) + Asbjørn (mini-review/comments from a library user) + Thomas M (a lot of suggestions) + Paul A. Bristow + Belcourt, Kenneth + John Bytheway +/- Yiannis Papadopoulos (there's already Bolt/Thrust for beginner and pure OpenCL for pros) +/- Vicente J. Botet Escriba (better docs and more performance tests) +/- Jason Newton (there was no explicit answer to the question "shuld be this library accepted into Boost?" but the review was positive in general) To sum up: Compute library becomes part of the Boost. Great thanks to all for the reviews and comments! Huge work was done and the issues raised are essential for library success. P.S.: Happy new year everyone! P.P.S.: Hope I did not miss some review! In case of any error, please let me know! -- Best regards, Antony Polukhin

1 0

[compute] review
by Vicente J. Botet Escriba 01 Jan '15

01 Jan '15

Hi, I have no time to do a complete review. Anyway here it is my minimal review *1. What is your evaluation of the design?** *** I would prefer that the algorithms take as first parameter the queue (which could be abstracted to an asynchronous executor). The performances let think that there is no interest in using the library for containers having less than 10^4/10^5 elements. Even if this is considered a low level library, the documentation should show how a library writer could make use of the provided interface to provide a higher one. I would prefer that the library make use of std::future or boost::future class instead of adding an additional one. Do the author tried to make use of the existing futures? if yes, which problems were found? I'm missing a range interface to most of the algorithms. I suspect that as this is a C++03 library it doesn't take advantages of some interesting C++11+/C++14 features. It is not clear which operations are synchronous, which ones could block, ... In order to get the native OpenCl handle I suggest to name the function get_native_handle instead of get. *2. What is your evaluation of the implementation?* I've not see at the implementation. *3. What is your evaluation of the documentation?* The documentation lacks of some core tutorials. I was unable to have an idea of what a context is, what can be done with a command_queue, what is a Kernel, a pipe, ...? Does it mean that the user must know OpenCL? The reference documentation should follow he C++ standard way, including pre-conditions, effects, synchronization, throws clauses. I would appreciate a description of the algorithms used, how the parallelism is used? is this completely managed by OpenCL or do the library something else? *4. What is your evaluation of the potential usefulness of the library?** *** This is essentially an optimization library. It should be quite useful, but the performances results don't probe it. *5. Did you try to use the library? With what compiler? Did you have any problems?** * No.* *** *6. How much effort did you put into your evaluation? A glance? A quick reading? In-depth study?** *** A glance. *7. Are you knowledgeable about the problem domain?* Yes and not. I don't know about OpenCL, but I'm aware of the current parallel proposals. *8. Do you think the library should be accepted as a Boost library? ** * As I have not taken too much time I'm unable to say that this library should not be included in Boost. So I vote to include it conditionally, subject to: * I would need some performances that probe the library is better than using standard STL containers in most of the cases. * The documentation should be completed with more tutorials and a better reference documentation. Best, Vicente

4 4