<div dir="ltr">Hi,<div><br></div><div>Last night I grabbed a trivial OpenCL sample code that does vector addition (source [1]) and threw in an atomic add on floats: <a href="https://pastee.org/8jtbj">https://pastee.org/8jtbj</a></div><div>Would this work as a starting point?</div><div><br></div><div>If this is too trivial, one option for extending it is to e.g. generate a trivial neighbor list (e.g. a random list of index pairs into a coordinate array) that the kernel looks over and calculate a distance (or some simple pair potential-like function).</div><div><br></div><div>Cheers,</div><div class="gmail_extra"><div><div class="gmail_signature">--<br>Szilárd</div></div><div class="gmail_signature"><br></div><div class="gmail_signature">[1] <a href="https://www.olcf.ornl.gov/tutorials/opencl-vector-addition/#vecAdd.c" target="_blank">https://www.olcf.ornl.gov/tutorials/opencl-vector-addition/#vecAdd.c</a><br></div><div class="gmail_signature"><br></div>
<br><div class="gmail_quote">On Thu, Dec 10, 2015 at 4:56 PM, Szilárd Páll <span dir="ltr"><<a href="mailto:pall.szilard@gmail.com" target="_blank">pall.szilard@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><div dir="ltr">Vedran,<div><br></div><div>Unfortunately, don't think I will have enough time at least in the coming 1-2 weeks. I could help composing the kernel, but that's likely going to be little effort and I am quite inexperienced with OpenCL, especially with the API "glue" code needed to just have a small test kernel running.</div><div><br></div><div>I could pith in with putting together the kernel, but if the goal is to have a simple test for global memory atomic addition on floats, perhaps the best idea is to strip down an SDK example* like a float vector addition (or reduction) and replace the regular global memory writes with the atomicAdd_g_f() function implemented in src/gromacs/mdlib/nbnxn_ocl/vectype_ops.clh.</div><div class="gmail_extra"><br></div><div class="gmail_extra"><br></div><div class="gmail_extra">* Both the AMD SDK and NVIDIA's ancient OpenCL SDK should have ready code, but having checked briefly, a slight stripping down may be needed to remove certain optimizations and avoid utility functions.</div><div class="gmail_extra"><br></div><div class="gmail_extra">Cheers,<br clear="all"><div><div>--<br>Szilárd</div></div><div><div class="h5">
<br><div class="gmail_quote">On Wed, Dec 9, 2015 at 10:30 AM, Vedran Miletić <span dir="ltr"><<a href="mailto:rivanvx@gmail.com" target="_blank">rivanvx@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><span>2015-12-04 18:13 GMT+01:00 Szilárd Páll <<a href="mailto:pall.szilard@gmail.com" target="_blank">pall.szilard@gmail.com</a>>:<br>
> Sounds good, is there anything on our side we can help with?<br>
><br>
> Cheers,<br>
><br>
> --<br>
> Szilárd<br>
><br>
<br>
</span>Szilard,<br>
<br>
actually, there is something that would be very useful, as I am<br>
struggling with testing my changes at the moment. It would be great to<br>
have minimal self-contained OpenCL example programs covering a<br>
spectrum of features we use. As a start, I could use a minimal atomic<br>
compare and swap example that would crash in the same way GROMACS does<br>
now.<br>
<br>
LLVM requires tests for all patches [1]. So I would certainly reuse these.<br>
<br>
Is this doable? I can try to make them myself, but you mentioned you<br>
are familiar with the code so I'm hoping you could make them quicker.<br>
<br>
Regards,<br>
Vedran<br>
<br>
[1] <a href="http://llvm.org/docs/DeveloperPolicy.html" rel="noreferrer" target="_blank">http://llvm.org/docs/DeveloperPolicy.html</a><br>
<div><div><br>
--<br>
Vedran Miletić<br>
<a href="http://vedranmileti.ch/" rel="noreferrer" target="_blank">http://vedranmileti.ch/</a><br>
--<br>
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