Re: [Myrinet] hybrid mpich support

Hi Kevin,

On Mon, 2002-10-07 at 18:21, Van Maren, Kevin wrote:
> Here is a patch, relative to the 1.2.4..8a release, that
> adds the ability to restrict shared memory on a SMP to
> only those processes that use the same Myrinet interface.

A similar patch is already in the CVS (1.2.4..8b is close to release).

> I developed this code to do some experimentation on a
> NUMA-ish machine, but I thought it may be more generally
> useful.  It is not complete (MPD support isn't runtime-
> tunable nad is untested), but I would appreciate feedback/
> comments on the code.  It works for me, but YMMV.

It is much simpler than that: shared memory should be always disabled
when the receive mode is not polling. When using blocking or hyrid, the
ch_gm device may block, and it's forbidden in a multi-device
configuration with MPICH.

The code looks like that:

  /* Set the shared memory support */
  if (gmpi.gm_receive_mode == gm_receive)
    {
      if (gmpi_shmem == NULL) 
        {
          gmpi.shmem = 1;
        }
      else
        {
          if (strcmp (gmpi_shmem, "1") == 0) 
            {
              gmpi.shmem = 1;
            }
          else
            {
              gmpi.shmem = 0;
            }
        }
    }
  else
    {
      gmpi.shmem = 0;
    }

 
> Also included is a fix for shared memory (Myricom #13195)
> to correct the mmap() size calculation, and some changes
> to eliminate warnings (unsigned i < 0 comparisons).

The mmap change is also already committed, but I will take the warnings
patch :-)

Thanks Kevin.

Patrick
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|   Patrick Geoffray, Ph.D.      [email protected] 
|   Myricom, Inc.                http://www.myri.com
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