Yan CRL Li <liyan...@cn.ibm.com> wrote on 12/10/2010 05:35:06 AM:

> For this scenario, I know the IP address of each node, I want to know 
each
> Place id corresponding to this IP.
> 
> For example :I put different files on these nodes. I start 5 places on 
two
> physical nodes:
> File A, File B are on node 1 with IP: 192.168.1.1
> FileC,File D and File E anre on node 2 with IP :192.168.1.2
> 
> When I access these Files, I need to know the mapping relationship 
between
> Place ID and IP address.
> 
> But when programming with X10, I only know the place id, I do not know
> which node is mapping to this id, how can I do this ?

Yan,

The mapping of places to nodes is external to X10.

When you launch using the sockets or MPI transport, you specify the host 
list
as one of the parameters.  The hosts will be picked out of the host list 
in a
round-robin fashion, so you know exactly which host corresponds to which
place.

If you use an external launcher, e.g., SLURM, you would have to look at 
the
documentation for that system to see how to force it to use particular 
nodes
as specific places.

The usual approach is to have a shared filesystem, put all 5 files on it,
and let each node access the file that corresponds to its place.  I 
realize
that the files may be too large for this to be immediately feasible, but
disk space is cheap, and it may end up being the most general solution.
        Igor
-- 
Igor Peshansky  (note the spelling change!)
IBM T.J. Watson Research Center
X10: Parallel Productivity and Performance (http://x10-lang.org/)
XJ: No More Pain for XML's Gain (http://www.research.ibm.com/xj/)
"I hear and I forget.  I see and I remember.  I do and I understand" -- 
Xun Zi


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