[Llvm-bgq-discuss] compilation + core dump question

[Hal Finkel]

----- Original Message -----
> Hal,
> 
> > I don't understand what you're trying to do there. If that
> > executable was
> > compiled with bgclang, and linked against PAMI, etc. then it can't
> > be run on
> > the frontend node. Can you explain?
> 
> Unfortunately, the depth of my ignorance is quite profound. Having
> spent years using crays where I could usually run executables
> compiled for the compute nodes, on the front end nodes, I just
> assumed that there'd be the same chips on the front end as the CN
> and most stuff would run ok. turns out this is far from true and so
> I will await the machine coming up again to experiment more.
> 
> (The code I compiled using xl did run on the front end though)

Generally speaking, you cannot run applications linked against the MPI libraries on the frontend (nor can you run anything that ends up containing QPX vector instructions, as the frontend nodes don't support those). The compute nodes have a different architecture and a different operating system, so this is truly a cross-compilation situation.

Every once in a while it will work, but don't count on it.

> 
> 
> > I used /tmp/bgclang as the example directory on the web page, but
> > you
> > might actually want to use someplace in your home directory ;)
> 
> Indeed. I'm ahead of you there. I had changed to my home dir, since
> the filesystem is being periodically wiped during installation,
> nothing is safe, so it hardly matters where I put stuff :)
> 
> Thanks for the help - especially to whoever is responsible for
> getting the clang rpms made, this is really magic. I can't compile
> my C++!! stuff with xl, so seeing this work out of the box makes me
> very happy.

That was a couple days of my life; I'm glad they're useful :)

 -Hal

> 
> JB
> 

-- 
Hal Finkel
Assistant Computational Scientist
Leadership Computing Facility
Argonne National Laboratory