Open MPI logo

Open MPI Development Mailing List Archives

  |   Home   |   Support   |   FAQ   |   all Development mailing list

Subject: Re: [OMPI devel] [OMPI svn-full] svn:open-mpi r25445
From: Nathan T. Hjelm (hjelmn_at_[hidden])
Date: 2011-11-08 08:57:38

Sure, I can do that. My only concern is with sending between hosts of
different endianness.

For example, if seg_key is 128 bits wide and the key32 is 64 bits then we
might run into this:

Host 1: (big endian)
Set seg_key.key32[0] = 0x11111111

would result in seg_key: 0x00000000 0x00000000 0x11111111 0x00000000

Host 2: (little endian)
Set seg_key.key32[0] = 0x111111111

would result in seg_key: 0x11111111 0x00000000 0x00000000 0x00000000

If either host were to send the other one its seg_key and try to use the
key32 they would get garbage. I haven't tested this case yet but I can test
on a PPE of RR later today.


On Tue, 8 Nov 2011 08:26:04 -0500, Jeff Squyres <jsquyres_at_[hidden]> wrote:
> On Nov 7, 2011, at 9:48 PM, Nathan T. Hjelm wrote:
>> In retrospect I should have done a RFC for the 3rd change with a short
>> timeout. At the time (operating on little sleep) it seemed like the
> commits
>> would have minimal impact. Please let me know if the commits have any
>> negative impact.
> FWIW, I think I'd like to see a rollback of the increase of array sizes
> the seg_key union. They weren't necessary and might be slightly
> misleading.
> --
> Jeff Squyres
> jsquyres_at_[hidden]
> For corporate legal information go to:
> _______________________________________________
> devel mailing list
> devel_at_[hidden]