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,
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<div class='path'>path: <a href='/guix/log/?id=0be51fe03bf2b8f3ef009929fa0860e17aa15de4'>root</a>/<a href='/guix/log/gnu?id=0be51fe03bf2b8f3ef009929fa0860e17aa15de4'>gnu</a>/<a href='/guix/log/gnu/tests?id=0be51fe03bf2b8f3ef009929fa0860e17aa15de4'>tests</a>/<a href='/guix/log/gnu/tests/ganeti.scm?id=0be51fe03bf2b8f3ef009929fa0860e17aa15de4'>ganeti.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/tests/ganeti.scm?id=0be51fe03bf2b8f3ef009929fa0860e17aa15de4&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2023-09-08 18:53:46 +0800'>2023-09-08</span></td><td><a href='/guix/commit/gnu/tests/ganeti.scm?id=a71ce15c73b211512e7eafbe325894a2be98845f'>services: ganeti: Fix tests.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/tests/ganeti.scm (run-ganeti-test)["force-start wconfd"]: Don't use
INVOKE.
["gnt-os list"]: Import (ice-9 textual-ports).
</span></span></td><td>Marius Bakke</td></tr>
<tr><td><span title='2023-02-09 01:07:47 +0100'>2023-02-09</span></td><td><a href='/guix/commit/gnu/tests/ganeti.scm?id=802ea1f3a43e5fb8d0b8bd2882954d8a6e49cde6'>system: Deprecate hosts-file.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/system.scm (operating-system-hosts-file): Deprecate procedure.
(warn-hosts-file-field-deprecation): New procedure, helper for
deprecated variable.
(operating-system)[hosts-file]: Use helper to warn deprecated field.
(local-host-aliases): Mark as deprecated.
(local-host-entries): New procedure.
(operating-system-default-essential-services,
hurd-default-essential-services): Use hosts-service-type.  Use
'%operating-system-hosts-file' and 'local-host-entries'.
(default-/etc/hosts): Remove procedure.
(operating-system-etc-service): Remove hosts file.
* doc/guix.texi (operating-system Reference)
(Networking Services) (Virtualization Services): Rewrite documentation
entries to use hosts-service-type.

Co-authored-by: Ludovic Courtès &lt;ludo@gnu.org&gt;
</span></span></td><td>Bruno Victal</td></tr>