As a temporary, non-portable substitute for hwloc, you can use the SPI calls that are described on my Wiki: https://wiki.alcf.anl.gov/parts/index.php/Blue_Gene/Q#Node_topology. I presume that this is the means by which hwloc will support BGQ when it does.
Blue Gene/Q has 16+1 cores with 4 hw threads each. Only 16 cores are visible to applications but as users can, in theory, run code on the 17th core (see https://wiki.alcf.anl.gov/parts/index.php/Blue_Gene/Q#17th_Core_App_Agents for how), it is important for these functions to return values in the range 0..16 and 0..67 instead of 0..15 and 0..63. I include this information in case users are confused about the additional range documented for these calls. Best, Jeff On Tue, Jan 8, 2013 at 11:10 AM, Brice Goglin <brice.gog...@inria.fr> wrote: > Hello Erik, > We need specific BGQ binding support, the binding API is different. Also we > don't properly detect the 16 4-way cores properly, we only only 64 identical > PUs. > I am supposed to get a BGQ account in the near future so I hope I will have > everything working in v1.7. > Stay tuned > Brice > > > > > Le 08/01/2013 18:06, Erik Schnetter a écrit : > > I am trying to use hwloc on a Blue Gene/Q. Building and installing worked > fine, and it reports the system configuration fine as well (i.e. it shows > all PUs). However, when I try to inquire the thread/core bindings, hwloc > crashes with an error in libc's free(). This is both with 1.6 and 1.6.1rc1. > > The error occurs apparently in CPU_FREE called from > hwloc_linux_find_kernel_nr_cpus. > > Does this ring a bell with anyone? I know this is not enough information to > debug things, but do you have any pointers for things to look at? > > I remember reading somewhere that the last bit in a cpu_set_t cannot be > used. A Blue Gene/Q has 64 PUs, and may be using 64-bit integers to hold > cpu_set_t data. Could this be an issue? > > My goal is to examine and experiment with thread/core bindings with OpenMP > to improve performance. > > -erik > > -- > Erik Schnetter <schnet...@gmail.com> > http://www.perimeterinstitute.ca/personal/eschnetter/ > > > _______________________________________________ > hwloc-users mailing list > hwloc-us...@open-mpi.org > http://www.open-mpi.org/mailman/listinfo.cgi/hwloc-users > > > > _______________________________________________ > hwloc-users mailing list > hwloc-us...@open-mpi.org > http://www.open-mpi.org/mailman/listinfo.cgi/hwloc-users -- Jeff Hammond Argonne Leadership Computing Facility University of Chicago Computation Institute jhamm...@alcf.anl.gov / (630) 252-5381 http://www.linkedin.com/in/jeffhammond https://wiki.alcf.anl.gov/parts/index.php/User:Jhammond
