PSM2 is the only valid implementation for OmniPath (OPA).  UCX also
supports OmniPath, but it does so via Verbs, thus getting much lower
performance (typically 3 GiB/s instead of 10 GiB/s).

To work around that, give the mtl_psm2 component a higher priority
than the pml_ucx component.

See <https://www.mail-archive.com/users@lists.open-mpi.org/msg33581.html>.

--- openmpi-4.0.2/ompi/mca/mtl/psm2/mtl_psm2_component.c	2019-11-15 17:06:15.142076840 +0100
+++ openmpi-4.0.2/ompi/mca/mtl/psm2/mtl_psm2_component.c	2019-11-15 17:06:22.242009379 +0100
@@ -126,7 +126,7 @@ ompi_mtl_psm2_component_register(void)
         setenv("PSM2_DEVICES", "self,shm", 0);
     }
 
-    param_priority = 40;
+    param_priority = 55;
     (void) mca_base_component_var_register (&mca_mtl_psm2_component.super.mtl_version,
                                             "priority", "Priority of the PSM2 MTL component",
                                             MCA_BASE_VAR_TYPE_INT, NULL, 0, 0,

Likewise for PSM: we want InfiniPath to be taken care of by PSM, not by UCX,
since UCX achieves worse performance.

--- openmpi-4.0.2/ompi/mca/mtl/psm/mtl_psm_component.c
+++ openmpi-4.0.2/ompi/mca/mtl/psm/mtl_psm_component.c
@@ -92,7 +92,7 @@ ompi_mtl_psm_component_register(void)
 
 
     /* set priority high enough to beat ob1's default */
-    param_priority = 30;
+    param_priority = 54;
     (void) mca_base_component_var_register (&mca_mtl_psm_component.super.mtl_version,
                                             "priority", "Priority of the PSM MTL component",
                                             MCA_BASE_VAR_TYPE_INT, NULL, 0, 0,
value='dbef037ff48460ec8f7bb4dbb3139c74403a9378'/><select name='qt'>
<option value='grep'>log msg</option>
<option value='author'>author</option>
<option value='committer'>committer</option>
<option value='range'>range</option>
</select>
<input class='txt' type='search' size='10' name='q' value=''/>
<input type='submit' value='search'/>
</form>
</td></tr></table>
<div class='path'>path: <a href='/guix/log/?id=dbef037ff48460ec8f7bb4dbb3139c74403a9378'>root</a>/<a href='/guix/log/gnu?id=dbef037ff48460ec8f7bb4dbb3139c74403a9378'>gnu</a>/<a href='/guix/log/gnu/packages?id=dbef037ff48460ec8f7bb4dbb3139c74403a9378'>packages</a>/<a href='/guix/log/gnu/packages/re2c.scm?id=dbef037ff48460ec8f7bb4dbb3139c74403a9378'>re2c.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/gnu/packages/re2c.scm?id=dbef037ff48460ec8f7bb4dbb3139c74403a9378&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2019-10-12 15:18:26 +0200'>2019-10-12</span></td><td><a href='/guix/commit/gnu/packages/re2c.scm?id=e4892ae3678e2ce7c726bd5f0bc12a08b5678639'>gnu: re2c: Update to 1.2.1.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/re2c.scm (re2c): Update to 1.2.1.

Signed-off-by: Sergei Trofimovich &lt;slyfox@inbox.ru&gt;
Signed-off-by: Ludovic Courtès &lt;ludo@gnu.org&gt;
</span></span></td><td>Sergei Trofimovich</td></tr>