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Subject: Re: [OMPI devel] descriptor limits -- FAQ item
From: Ralph Castain (rhc_at_[hidden])
Date: 2011-08-30 22:39:37


On Aug 29, 2011, at 4:22 PM, Eugene Loh wrote:

> It seems to me the FAQ item http://www.open-mpi.org/faq/?category=large-clusters#fd-limits needs updating. I'm willing to give this a try, but need some help first. (I'm even more willing to let someone else do all this, but I'm not holding my breath.)
>
> For example, the text sounds dated -- e.g., with references to v1.2. Is the "road map" discussion still current?

No - we should remove that stuff, as well as discussion of the 1.2 issues as we no longer support code that old.

>
> Is the estimate of the needed number of descriptors our current best guess?

No - it's incorrect.

>
> The FAQ is missing discussion of how to increase the limit. For something like "limit/ulimit/unlimit", where should this be done? In .login? I assume it's not sufficient simply to set this in the shell where mpirun is executed, assuming processes will also be launched on remote nodes. Yes?
>
> (And, clearly, the FAQ item is missing discussion of the MCA parameter opal_set_max_sys_limits.)

I'll take a first cut at it - may leave the discussion of how to increase the limits to you.

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