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Subject: Re: [OMPI devel] How to disable paffinity
From: Jeff Squyres (jsquyres_at_[hidden])
Date: 2010-07-07 07:22:11

On Jul 6, 2010, at 10:48 PM, Õž§ wrote:

> 1.If I write a rlogin component ,

Is the command line of rlogin that much different than that of rsh/ssh? For example, can you just s/rsh/rlogin/ on the overall command line and have it just work?

If so, I suspect that tweaking the rsh plm might be far simpler than having your own component.

> can I just login in the node in the cluster and launch the process . If it is ,what the role the odls plays ??

ODLS = ORTE Daemon Local launch Subsystem.

PLM = Process Lifecycle Management.

Meaning: the PLM is used to launch orteds (more on this below) across multiple nodes. The ODLS is used to launch processes locally from the orted (e.g., via POSIX fork/exec).

> 2.what is orted? Should the orted exists in every node and functions as a node process launch proxy ?

Yes. The orted = ORTE daemon. It is almost always the first thing launched on each node and acts as a proxy for launching, killing, and monitoring the user's applications on each node. It also does other control kinds of things, like relay stdout/stderr back up to the HNP (more below), etc.

> 3,what is hnp ? Is every job has only one hnp ,and when I use mpirun , the mpirun process is hnp ??

HNP = head node process, meaning mpirun (or actually, orterun -- mpirun is a symlink to orterun). The HNP functions as an orted as well, so it can use the ODLS to launch processes locally, etc.

Ralph can provide more detail on all of the above, but these are the basics.

Jeff Squyres
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