Open MPI logo

Open MPI Development Mailing List Archives

  |   Home   |   Support   |   FAQ   |   all Development mailing list

Subject: [OMPI devel] RFC: PML/CM priority
From: Rainer Keller (keller_at_[hidden])
Date: 2009-08-11 14:33:24


Hello all,
as raised on todays telcon:

WHAT: Obeying or lowering default priority of PML/CM.

WHY: Not obvious why MTLs are not used for Portals/MX

WHEN: On trunk, Tuesday afternoon 18 Aug 2009
      On 1.3 by CMR on 25 Aug 2009

TIMEOUT: Tuesday telconf, 18 Aug 2009

---------------------------------------------------------------

When compiling on systems with MX or Portals, we offer MTLs and BTLs.
If MTLs are used, the PML/CM is loaded as well as the PML/OB1.

The current default priority for them is:
@jaguar13:~> ompi_info --param pml all | grep priority
MCA pml: parameter "pml_cm_priority" (current value: <30>, ...)
MCA pml: parameter "pml_ob1_priority" (current value: <20>, ...)

Now in pml_cm_component.c:113 the priority however is changed:
    } else if(strcmp(ompi_mtl_base_selected_component->
mtl_version.mca_component_name, "psm") != 0) {
         /* if mtl is not PSM then back down priority, and require user to*/
         /* specify pml cm directly if that is what they want priority */
         /* of 1 is sufficient in that case as it is the only pml that */
         /* will be considered */
         *priority = 1;
    }
which is kind of "unexpected" to the user ;-)
This moved into trunk in r13576. I had a off-list mail with Galen on the
reasoning of this part of the patch, now I would like to address the
community.

Question 1: Is favoring OB1 over CM required for any MTL (MX, Portals, PSM)?

Question 2: If it is, I would like to reflect this in the default priorities,
aka have CM have a priority lower than OB1 and in the case of PSM raising it.

I'd like to raise any issues until next week's telcon.

Actions Taken:

If no objections are raised for Question 1, I would like to remove the
lowering of the CM's priority and have it always favoured over OB1.

If there are issues with that, I would like to patch such that:

svn diff pml_cm_component.c
Index: pml_cm_component.c
===================================================================
--- pml_cm_component.c (revision 21786)
+++ pml_cm_component.c (working copy)
@@ -106,7 +106,7 @@
                            "CM PML selection priority",
                            false,
                            false,
- 30,
+ 10,
                            &ompi_pml_cm.default_priority);

     return OMPI_SUCCESS;
@@ -139,12 +139,12 @@
     if (OMPI_SUCCESS != ret) {
         *priority = -1;
         return NULL;
- } else if(strcmp(ompi_mtl_base_selected_component-
>mtl_version.mca_component_name, "psm") != 0) {
+ } else if(strcmp(ompi_mtl_base_selected_component-
>mtl_version.mca_component_name, "psm") == 0) {
- /* if mtl is not PSM then back down priority, and require the user
to */
- /* specify pml cm directly if that is what they want priority */
- /* of 1 is sufficient in that case as it is the only pml that */
- /* will be considered */
- *priority = 1;
+ *priority = 30;
     }
/* modulo updating the comment */

Best regards,
Rainer

-- 
------------------------------------------------------------------------
Rainer Keller, PhD                  Tel: +1 (865) 241-6293
Oak Ridge National Lab          Fax: +1 (865) 241-4811
PO Box 2008 MS 6164           Email: keller_at_[hidden]
Oak Ridge, TN 37831-2008    AIM/Skype: rusraink