<div dir="ltr"><br><br><div class="gmail_quote">On Fri, Aug 1, 2008 at 3:48 PM, David van der Spoel <span dir="ltr"><<a href="mailto:spoel@xray.bmc.uu.se">spoel@xray.bmc.uu.se</a>></span> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
Roland Schulz wrote:<br>
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On Fri, Aug 1, 2008 at 4:47 AM, David van der Spoel <<a href="mailto:spoel@xray.bmc.uu.se" target="_blank">spoel@xray.bmc.uu.se</a> <mailto:<a href="mailto:spoel@xray.bmc.uu.se" target="_blank">spoel@xray.bmc.uu.se</a>>> wrote:<div class="Ih2E3d">
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<a href="mailto:chris.neale@utoronto.ca" target="_blank">chris.neale@utoronto.ca</a> <mailto:<a href="mailto:chris.neale@utoronto.ca" target="_blank">chris.neale@utoronto.ca</a>> wrote:<br>
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Roll back to gcc 3.x.<br>
<br>
There is information available that says something like "don't<br>
use gcc 4.x, it is broken", but I stand by my previous comments<br>
that it is unfortunate that it is up to the end user to search<br>
the gromacs archives to find this out, not withstanding that it<br>
is a gcc-based problem.<br>
<br>
In my opinion, you're fortunate to have found this out and there<br>
are probably *lots* of people running gcc 4.x installations of<br>
gromacs right now.<br>
<br>
<br>
We discussed including the test set with the distribution, which<br>
would simplify the procedure, but decided against it, because the<br>
distribution would become a lot bigger.<br>
<br>
Maybe we should reconsider this?<br>
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I think we also need some larger tests with few hundred thousands up to a few million atoms. Because I had several issues in the last weeks that mdrun binaries with different compilers were all working fine with smaller systems but gave total different results (became unstable) with some compiler (I had problems with: gcc 4.2.0 with barcelona patches, pgi, IBM xlc, it worked with gcc 4.2.4 and pathscale). Without common tests for these larger systems it is hard to report these problems.<br>
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>From a software point of view this is just coincidence.</blockquote><div>I agree that this is often the case but not always. There was e.g. a (rounding) problem in the domain decomposition which only occurred when using more than 20 or so cells in one dimension. You can only find this with really large tests. <br>
</div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"> Often it turns out that if you hit such a problem, be it due to the software or due to the compiler, that you can reduce the size of the still reproduce it. But more tests and more diverse tests would be good. We don't have any coarse grained tests, and very few non-water tests. However, you don't want to run hundreds of tests for each installation, so the problem remains...</blockquote>
<div>Yes I agree. <br><br>I guess I'm not really talking about the current test-set for installation tests. You don't want to go trough Million atoms test for each installation.<br><br>I think we should have an additional test-set for manual testing. Mainly to help write bug-reports for MPI related problems. So that you can write the bugreport with a known, shared test-case in case you aren't able to reduce the problem to a small case (yourself).<br>
</div><div> </div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
Maybe we should endorse a few specific compilers (and versions), and bail out on others, unless you force configure to use those?</blockquote><div>I think this is a great idea. And even better if we combine it with a nightly test-built on all endorsed compilers. We could use <a href="http://buildbot.net/trac">http://buildbot.net/trac</a> for that. I'm happy to provide nightly build and test run results for the systems I have access to. I can also help setting up the automatic build server.<br>
<br>Roland<br></div></div><br clear="all"><br>-- <br>Center for Molecular Biophysics ORNL/UT <a href="http://cmb.ornl.gov">cmb.ornl.gov</a><br>
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