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Subject: Re: [OMPI devel] question about vpid
From: Ralph Castain (rhc_at_[hidden])
Date: 2011-07-29 14:11:22


There are no hard rules, but some practical ones. In theory, you can use any value so long as it is unique. In practice, that can cause problems as several arrays are sized by the vpid value. So a really big vpid causes the array to be sized to accommodate at least that many values.

In other words, the system was designed as if vpids would be continuous, starting from zero.

This is something I plan to adjust in the not-too-distant future as sparse arrays of nodes, procs, and even jobs are becoming more common.

On Jul 29, 2011, at 12:06 PM, Maurice Feskanich wrote:

> Hi All,
>
> I have a question about the vpid values. Do they have to start with zero or one, and do they have to have no gaps in the sequence? Basically, I'm wondering if I can use any arbitrary integer, as long as they are unique. If I can, is there a maximum value?
> Thanks,
>
> Maury Feskanich
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