On Tue, 2011-04-12 at 19:33, Mark Howison wrote: > Hi Leigh and Mark, > > I'm just getting caught up on this thread now and wanted to add a few > comments: > > 1) The idea of passing off a baton to serialize access to a file is > something we tried in H5Part when we ran into a problem around 16K > concurrency where Lustre would actually *time out*
I don't have a lot of data on this but on our BG/P-Lustre installation, we've gone up to 128,000 files writing a file-per-processor without incident. I think we've also run 64,000 cpus writing to 256 files using baton passing a la pmpio.h without incident. I think Leigh may have inquired about VisIt using pmpio.h in any of its plugins; No, it doesn't. But, VisIt is more or less only reading the files and most (not all but most) plugins in VisIt are designed around the poor man's parallel I/O model. I don't think we have any performance data for VisIt for rich man's or poor man's parallel I/O. Mark -- Mark C. Miller, Lawrence Livermore National Laboratory ================!!LLNL BUSINESS ONLY!!================ [email protected] urgent: [email protected] T:8-6 (925)-423-5901 M/W/Th:7-12,2-7 (530)-753-8511 _______________________________________________ Hdf-forum is for HDF software users discussion. [email protected] http://mail.hdfgroup.org/mailman/listinfo/hdf-forum_hdfgroup.org
