RSH scaling problems...

Jeff Layton jeffrey.b.layton at
Tue Dec 17 09:15:48 PST 2002

Greg Lindahl wrote:

> On Tue, Dec 17, 2002 at 06:09:07AM -0500, Jeff Layton wrote:
> >    So, even if you patch the kernel to give you more than 256 ptys,
> > you also need to patch rcmd() to use a wider range of ports (at least
> > in theory).
> >    Any comments?
> rcmd must use low ports, for security reasons.
> ssh has a mode in which it can use a high port. That's how the
> 370-node FSL system did it in 1999. This technique also worked OK on
> Cplant at 1200 nodes.


   Our users who have tested ssh have told us that the wall clock
time is much larger than if they use rsh (I'm sorry I don't have any
numbers :) This are MPI jobs running over about 12-24 hours.
Have you seen this?



> -- greg
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Jeff Layton
Senior Engineer
Lockheed-Martin Aeronautical Company - Marietta
Aerodynamics & CFD

"Is it possible to overclock a cattle prod?" - Irv Mullins

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