On Mar 3, 2010, at 1:24 PM, Jeff Squyres wrote:

> I'm not sure I agree with change #1.  I understand in principle why the 
> change was made, but I'm uncomfortable with:
> 
> 1. The individual entries now behave like pseudo-regexp's rather that strict 
> matching.  We used strict matching before this for a reason.  If we want to 
> allow regexp-like behavior, then I think we should enable that with special 
> characters -- that's the customary/usual way to do it.

The history of this particular piece of code is that it used to use strncmp.  
George Bosilca changed it last summer, incidental to a larger change (r21652).  
The commit comment was not particularly illuminating on this issue, in my 
opinion:

http://www.open-mpi.org/hg/hgwebdir.cgi/ompi-svn-mirror/rev/bde31d3db7ba

> 2. All other <foo>_in|exclude behavior in ompi is strict matching, not prefix 
> matching.  I'm uncomfortable with the disparity.

That turns out not to be the case.  Look in 
btl_tcp_proc.c/mca_btl_tcp_retrieve_local_interfaces.

> Additionally, if loopback is now handled properly via change #2, shouldn't 
> the default value for the btl_tcp_if_exclude parameter now be empty?

That's a good question.  Enabling the "lo" interface results in intra-node 
messages being striped across that interface in addition to the others on a 
system.  I don't know what impact that would have, if any.

> Actually -- thinking about this a little more, does opal_net_islocalhost() 
> guarantee to work on peer interfaces?  

It looks to see whether the IP address is (v4) 127.0.0.1, or (v6) ::1.  I 
believe that these values are dictated by the relevant RFCs (but I haven't 
looked to make sure).

Iain

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