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<p><font size="2" face="sans-serif">It's just that providing a "more meaningful" key can help when debugging or managing through the OS. You still have to generate some sort of "sequence" number per-communicator, as successive allocations on the same communicator must return different memory. So, communicator alone is not enough to uniquely identify/select an allocation. Implementations will have to generate a "key" to pass to the OS, and so all ranks must be able to generate identical keys for corresponding calls. </font><br>
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<font size="2" face="sans-serif">_______________________________________________<br>
Douglas Miller BlueGene Messaging Development<br>
IBM Corp., Rochester, MN USA Bldg 030-2 A410<br>
dougmill@us.ibm.com Douglas Miller/Rochester/IBM</font><br>
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<img width="16" height="16" src="cid:1__=09BBFD61DFDDB7608f9e8a93df938@us.ibm.com" border="0" alt="Inactive hide details for Pavan Balaji ---12/07/2010 08:08:55 AM---On 12/07/2010 07:58 AM, Douglas Miller wrote:"><font size="2" color="#424282" face="sans-serif">Pavan Balaji ---12/07/2010 08:08:55 AM---On 12/07/2010 07:58 AM, Douglas Miller wrote:</font><br>
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<ul style="padding-left: 72pt"><font size="1" face="sans-serif"><b>Pavan Balaji <balaji@mcs.anl.gov></b></font><font size="1" face="sans-serif"> </font>
<p><font size="1" face="sans-serif">12/07/2010 08:08 AM</font></ul>
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<ul style="padding-left: 7pt"><font size="1" face="sans-serif">mpi3-hybridpm@lists.mpi-forum.org</font></ul>
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<ul style="padding-left: 7pt"><font size="1" face="sans-serif">Douglas Miller/Rochester/IBM@IBMUS</font></ul>
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<ul style="padding-left: 7pt"><font size="1" face="sans-serif">Re: [Mpi3-hybridpm] Hybrid WG meeting at the Forum</font></ul>
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<tt><font size="2"><br>
On 12/07/2010 07:58 AM, Douglas Miller wrote:<br>
> In order to ensure all nodes get the same memory segment, they all have<br>
> to use the same "key". At least if this is implemented on Unix SysV or<br>
> POSIX shmem. Then there's the possibility of some nodes allocing on a<br>
> sub-comm first, etc. I think its just avoiding a lot of potential<br>
> complications and don't see what the downside is.<br>
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In that sense, isn't the communicator a "key"?<br>
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-- Pavan<br>
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-- <br>
Pavan Balaji<br>
</font></tt><tt><font size="2"><a href="http://www.mcs.anl.gov/~balaji">http://www.mcs.anl.gov/~balaji</a></font></tt><tt><font size="2"><br>
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