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,
e='hidden' name='id' value='d627fbad8f4e157103251b07d7543dd2f5647cea'/><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=d627fbad8f4e157103251b07d7543dd2f5647cea'>root</a>/<a href='/guix/log/gnu?id=d627fbad8f4e157103251b07d7543dd2f5647cea'>gnu</a>/<a href='/guix/log/gnu/build?id=d627fbad8f4e157103251b07d7543dd2f5647cea'>build</a>/<a href='/guix/log/gnu/build/activation.scm?id=d627fbad8f4e157103251b07d7543dd2f5647cea'>activation.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/build/activation.scm?id=d627fbad8f4e157103251b07d7543dd2f5647cea&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2021-07-29 11:32:08 -0400'>2021-07-29</span></td><td><a href='/guix/commit/gnu/build/activation.scm?id=a7ac19851baab3fbcc40c4b2cf5b00a6ac9cd2f3'>services: setuid: More configurable setuid support.</a><span class='msg-avail'>...</span></td><td>Chris Lemmer-Webber</td></tr>
<tr><td><span title='2021-04-03 22:08:34 +0200'>2021-04-03</span></td><td><a href='/guix/commit/gnu/build/activation.scm?id=2161820ebbbab62a5ce76c9101ebaec54dc61586'>activation: Do not dereference symlinks during home directory creation.</a><span class='msg-avail'>...</span></td><td>Maxime Devos</td></tr>
<tr><td><span title='2021-03-10 18:01:47 +0100'>2021-03-10</span></td><td><a href='/guix/commit/gnu/build/activation.scm?id=520bac7ed00a949a0391ad680de65a1498105c2b'>services: Prevent following symlinks during activation.</a><span class='msg-avail'>...</span></td><td>Maxime Devos</td></tr>
<tr><td><span title='2021-02-09 10:06:02 +0100'>2021-02-09</span></td><td><a href='/guix/commit/gnu/build/activation.scm?id=aa8de806252e3835d57fab351b02d13db762deac'>activation: Do not make setuid programs setgid-root [security].</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2020-06-09 10:43:54 +0200'>2020-06-09</span></td><td><a href='/guix/commit/gnu/build/activation.scm?id=ea80cdbcea3763ded87d2fc3b5e97a427a6bb1d4'>activation: Fix function call for system activation</a><span class='msg-avail'>...</span></td><td>Royce Strange</td></tr>
<tr><td><span title='2020-06-08 14:12:20 +0200'>2020-06-08</span></td><td><a href='/guix/commit/gnu/build/activation.scm?id=c3fd2df705695a0dc9f393545606360be1ea6104'>system: Support activation service for the Hurd.</a><span class='msg-avail'>...</span></td><td>Jan (janneke) Nieuwenhuizen</td></tr>