Mar 5, 2011

I ran into some surprising behavior a little while back while hacking on the MPICH2 build system, that I thought I should mention here.  But first, some background info is in order.  We have numerous subsystems that are currently configured (in the autoconf sense) by running an autoconf-generated configure script from various points in the top level configure.  Think AC_CONFIG_SUBDIRS, but the subconfig happens at the place where the macro is used, rather than being deferred to config.status-time.  There are some advantages to this scheme, but there are two fairly severe disadvantages:

Jan 21, 2011

Last weekend I got to try ice climbing out at the Ice Pit near Green Bay, Wisconsin.  It was a very cool setup, sort of an outdoor ice climbing gym in an active quarry.  Normally you must be a member to climb there, but for the festival it was just $20 for the whole weekend.  I did the trip with five other guys, all rock climbers, three of which also work at the Lab.

Jan 20, 2011

Quick MPICH2 tip: passing the “-l” option to MPICH2’s mpiexec (hydra) yields rank-labled output like so:

% mpiexec -l -n 2 ./examples/cpi
[0] Process 0 of 2 is on g2-2.local
[1] Process 1 of 2 is on g2-2.local
[0] pi is approximately 3.1415926544231318, Error is 0.0000000008333387
[0] wall clock time = 0.000210

This is handy for figuring out which process is printing what without reaching in and modifying all of your printf statements to explicitly print the rank as well.

Jan 20, 2011

Dave following on “Το ονειρο και ο φοβος” (Google trans. “The dream and the fear”), 5b (approx. 5.8+), in Agio Farango, Crete, Greece.

I had business on Crete, Greece and was fortunate enough to be able to stay an extra day for some sport climbing.  We were staying east of Heraklion, near Hersonissos, so Agio Farango, on the south side of the island seemed the best option for a day trip.  We picked up a guide book online ahead of time, rented a car, and headed southwest about 100 km or so, probably 2.5 hours each way, to Kali Limenes.