From: Lars Rzymianowicz Newsgroups: comp.parallel.mpi Subject: Re: MPI as root on SGI PowerChallenge Date: Fri, 21 Aug 1998 08:52:31 +0200 Organization: Dept. of Computer Engineering, University of Mannheim, Germany Message-Id: <35DD192F.BDDA8DD8@mufasa.informatik.uni-mannheim.de> References: <35DCE5F6.B563DD17@esv1.auckland.ac.nz> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Michael Somervell wrote: > [...] To time my algorithms > accurately, I need to have exclusive access to multiple processors, and > the only way to do this is to have root access. All seems fine and good > until I actually try and run my programs using mpirun ("mpirun -np 8 > synchronous") when logged in as root (and no, I am not the > administrator, but he has kindly allowed me to run my algorithms as > root.) The error "MPI: could not run executable" appears every time, [...] Using rsh as root will always ask for a password, whether there is a .rhosts file or not. So MPI struggles, because the rlogin is denied by the system. The reason is clear: You don't want a root of one machine become root on all others. Solution: run the apps as normal user. If you need a dedicated system for performance evaluation, your sysadmin should be able to configure the system in a way, that only you are allowed to login for a specific time. Lars -- email: lr@mufasa.informatik.uni-mannheim.de Homepage: http://mufasa.informatik.uni-mannheim.de/lsra/persons/lars/