Users June 2013

users@lists.einsteintoolkit.org

13 participants
24 discussions

Einstein Toolkit Conference Call Reminder
by Erik Schnetter 09 Jun '13

09 Jun '13

You are cordially invited to join our weekly Einstein Toolkit conference call at 10:00 US central time every Monday. Instructions for joining this or other events are at <http://einsteintoolkit.org/community/support/>. The phone number for the upcoming call is +1-866-573-0359 (or +1-225-578-4942 from outside the US), and the conference ID is 118682#. Feel free to bring any topics with you when you join the call. Topics discussed last week included continued planning for the upcoming Einstein Toolkit developer workshop in July. As usual, we will also briefly review last week's discussions on the mailing list, which include - how to add a newline character to a string in Fortran (apparently one doesn't) - mvapich vs. IMPI on Stampede - how to define pi (aka: how to "fix" the C standard) - recent Carpet changes - recent GRHydro changes -erik -- Erik Schnetter <schnetter(a)cct.lsu.edu> http://www.perimeterinstitute.ca/personal/eschnetter/

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Recent Carpet changes
by Erik Schnetter 08 Jun '13

08 Jun '13

As announced in our weekly phone calls, I just committed a set of changes to Carpet. These changes will in the future significantly improve parallel scaling, but also touch much of the low-level code. There is thus a certain inherent danger that something broke. However, I expect that these build and run fine. The performance-improving features are disabled by default, and require setting compile-time flags to enable them. This will replace the current bboxset set class by a new implementation build on a tree structure. With this improvement, I was able to run Carpet on 260k cores (8k nodes) on Blue Waters. For the curious cats among us: these flags are -DCARPET_ENABLE_BBOXSET2: build (but do not use) the new class (for testing) -DCARPET_USE_BBOXSET2: use the new class instead of the old (if enabled) The new implementation requires certain C++11 features that may not be present on older compilers. In this case, you may have to set some of the macros below to activate work-arounds. You may also need to build the Boost library. -DCARPET_AVOID_LAMBDA: Use macros instead of lambda expressions Lambda expressions simplify writing iterators for data structures. -DCARPET_USE_BOOST_FOREACH: Use Boost's FOREACH instead of C++11 range-based for loops Range-based for loops are syntactic sugar for using iterators that (finally!) lead to shorter, simpler code when using iterators. -DCARPET_USE_BOOST_SHARED_PTR: Use Boost's shared_ptr instead of the C++11 shared_ptr shared_ptr automatically call delete when necessary when pointers go out of scope, simplifying code and increasing safety. -erik -- Erik Schnetter <schnetter(a)cct.lsu.edu> http://www.perimeterinstitute.ca/personal/eschnetter/

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Meeting Minutes
by Roland Haas 04 Jun '13

04 Jun '13

Present: Erik, Peter, Ian, Yosef, Matt, Roland automated tests: * want to run tests periodically on production machines rather than just in Ubuntu VM to test other compilers/MPI implementation than gcc/OpenMPI * Ian has setup for Datura under development, add other machines once system is stable. This method runs Jenkins on the head node. * add short (20min or so) simulation to tests to check more complex setups ET workshop: * David Rideout offered to give a presentation (private email to Erik, hope I did not get this wrong) * goals: ** ES wants to improve Carpet scalability to >10^4-10^5 processors ** (known) bottlenecks are: bboxset class, any lower-d IO which serializes it seems * PLEASE think of topics for the workshop and post them to the mailing list occasional hangs in MPI reported by Yosef: * hangs occur with or without the parity thorn * hangs occur on RIT cluster (with parity thorn, mvapich) * hangs occur on Stampede (no parity thorn, IMPI) * Ian saw codes hang in ibrun when MPI versions did not match, this seems to not be the case here Yours, Roland

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FW:
by Giovanni Corvino 02 Jun '13

02 Jun '13

http://new.sun-mif.com/jkvbo/aqthnsecvnqjnsxpakspnv.xcxvsnbyeq

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Users June 2013