Hello Tony, Thank you very much for your reply. I followed your advice and gave the hostname 'dragonfly' to my machine. Then, in /etc/hosts I provided gave the alias 'dragonfly' to localhost as you suggested: " marto@dragonfly% cat /etc/hosts ::1 localhost dragonfly 127.0.0.1 localhost dragonfly " I compiled both the icpi and hellow examples. Now mpiexec seems to work, although not as reliably as I might wish. Running any of the examples with one core like this: mpiexec -n 1 mpich-3.0.4/examples/hellow is always successful. I could never get the command to finish with 2, 3, or 4 cores: it simply hangs. E.g. with 2 cores after running the above command I get: " marto@dragonfly% ps x | grep hellow 166493 ?? I6s 0:00.00 mpich-3.0.4/examples/hellow 166494 ?? I6s 0:00.00 mpich-3.0.4/examples/hellow " With 5, 6, 7, or 8 cores most of the time the command is successful, that is all cores print as expected, but sometimes the command also hangs just as with 2 cores. Testing with icpi and 10^10 intervals gives the following output with 1 core: " marto@dragonfly% mpiexec -n 1 mpich-3.0.4/examples/icpi Enter the number of intervals: (0 quits) 10000000000 pi is approximately 3.1415926535895782, Error is 0.0000000000002149 wall clock time = 19.997830 " and the following with 5 cores, when it does not hang: " marto@dragonfly% mpiexec -n 5 mpich-3.0.4/examples/icpi Enter the number of intervals: (0 quits) 10000000000 pi is approximately 3.1415926535899605, Error is 0.0000000000001674 wall clock time = 4.475224 " As you can see, the calculation scales nicely. However, I am lost trying to figure out this unreliable behaviour. Maybe it has something to do with the hwloc warnings I get at configure? I am attaching the output of running the configure script. Thank you very much for your helpful advices. I am looking forward to your reply. Best regards, Martin On Fri, May 8, 2020 at 2:48 PM Tony Curtis <[email protected]> wrote:

On May 8, 2020, at 1:41 AM, Martin Ivanov <[email protected]> wrote:

Hello, Thank you for your replies. I think another version of MPICH may not work as I am following a tutorial ( https://www2.mmm.ucar.edu/wrf/OnLineTutorial/compilation_tutorial.php) that requires specific library versions. My /etc/hosts file contains only these two lines:

" ::1 localhost localhost.my.domain 127.0.0.1 localhost localhost.my.domain "

uname -n returns an empty string as I have not set a hostname. I guess I do not need this because I need to run MPICH only on this machine, that is on localhost? uname -a gives the following output:

Thing is, though, your initial post showed ssh being used as launcher. So in that case you would definitely need a hostname so you can resolve back to yourself (your shell prompt was a big clue, by the way). Setting a hostname and making it an alias of localhost in /etc/hosts would probably do wonders no matter the underlying launch.

The -info output is pretty much the same as I see on FreeBSD.

If you run a hello world with a sleep in it to allow you to react, what does “ps x” show?

(Not familiar much with DragonFly beyond “poking at it” so I don’t have any particular insight there.)

Tony