memattrs: add MemoryTiersNr=2 info attr to topology

Closes #661

Signed-off-by: Brice Goglin <Brice.Goglin@inria.fr>

doc/hwloc.doxy

@@ -2034,6 +2034,10 @@ placed.
 These info attributes are attached to the topology itself.
 
 <dl>
+<dt>MemoryTiersNr</dt>
+<dd>The number of different memory tiers in the topology, if any.
+See \ref heteromem.
+</dd>
 <dt>Backend</dt>
 <dd>The name of a hwloc backend/component that added objects in the topology.
 If several components were combined, multiple Backend pairs may exist,
@@ -2574,6 +2578,12 @@ $ hwloc-calc -I 'numa[tier=0]' -p all
 2,3
 \endverbatim
 
+The number of tiers may be retrieved at looking in topology attributes:
+\verbatim
+$ hwloc-info --get-attr "info MemoryTiersNr" topology
+2
+\endverbatim
+
 hwloc-calc and hwloc-bind also have options such as
 <tt>\--local-memory</tt> and <tt>\--best-memattr</tt>
 to select the best NUMA node among the local ones.

hwloc/memattrs.c

@@ -1,5 +1,5 @@
 /*
- * Copyright © 2020-2023 Inria.  All rights reserved.
+ * Copyright © 2020-2024 Inria.  All rights reserved.
  * See COPYING in top-level directory.
  */
 
@@ -1807,6 +1807,11 @@ hwloc__apply_memory_tiers_subtypes(hwloc_topology_t topology,
       }
     }
   }
+  if (nr_tiers > 1) {
+    char tmp[20];
+    snprintf(tmp, sizeof(tmp), "%u", nr_tiers);
+    hwloc__replace_infos(&topology->infos, "MemoryTiersNr", tmp);
+  }
 }
 
 int
@@ -1822,6 +1827,7 @@ hwloc_internal_memattrs_guess_memory_tiers(hwloc_topology_t topology, int force_
   while ((node = hwloc_get_next_obj_by_type(topology, HWLOC_OBJ_NUMANODE, node)) != NULL) {
     hwloc__remove_infos(&node->infos, "MemoryTier", NULL);
   }
+  hwloc__remove_infos(&topology->infos, "MemoryTiersNr", NULL);
 
   env = getenv("HWLOC_MEMTIERS");
   if (env) {

hwloc/topology-xml.c

@@ -1,6 +1,6 @@
 /*
  * Copyright © 2009 CNRS
- * Copyright © 2009-2023 Inria.  All rights reserved.
+ * Copyright © 2009-2024 Inria.  All rights reserved.
  * Copyright © 2009-2011, 2020 Université Bordeaux
  * Copyright © 2009-2018 Cisco Systems, Inc.  All rights reserved.
  * See COPYING in top-level directory.
@@ -458,6 +458,7 @@ hwloc__xml_import_obj_info(hwloc_topology_t topology,
           if (!strcmp(infoname, "Backend")
               || !strcmp(infoname, "SyntheticDescription")
               || !strcmp(infoname, "LinuxCgroup")
+              || !strcmp(infoname, "MemoryTiersNr")
               || !strcmp(infoname, "WindowsBuildEnvironment")
               || !strcmp(infoname, "OSName")
               || !strcmp(infoname, "OSRelease")

tests/hwloc/linux/64intel64-fakeKNL-SNC4-hybrid-msc.console

@@ -155,5 +155,5 @@ Memory attribute #2 name `Bandwidth' flags 5
   NUMANode L#5 = 90000 from cpuset 0x0f000f00,0x0f000f00 (Group0 L#2)
   NUMANode L#6 = 22500 from cpuset 0xf000f000,0xf000f000 (Group0 L#3)
   NUMANode L#7 = 90000 from cpuset 0xf000f000,0xf000f000 (Group0 L#3)
-Topology infos: Backend=Linux OSName=Linux OSRelease=3.10.0-327.el7.x86_64 OSVersion="#1 SMP Thu Oct 29 17:29:29 EDT 2015" HostName=localhost.localdomain Architecture=x86_64
+Topology infos: Backend=Linux OSName=Linux OSRelease=3.10.0-327.el7.x86_64 OSVersion="#1 SMP Thu Oct 29 17:29:29 EDT 2015" HostName=localhost.localdomain Architecture=x86_64 MemoryTiersNr=2
 Topology not from this system

tests/hwloc/linux/64intel64-fakeKNL-SNC4-hybrid.console

@@ -150,5 +150,5 @@ Memory attribute #2 name `Bandwidth' flags 5
   NUMANode L#5 = 90000 from cpuset 0x0f000f00,0x0f000f00 (L3 L#2)
   NUMANode L#6 = 22500 from cpuset 0xf000f000,0xf000f000 (L3 L#3)
   NUMANode L#7 = 90000 from cpuset 0xf000f000,0xf000f000 (L3 L#3)
-Topology infos: Backend=Linux OSName=Linux OSRelease=3.10.0-327.el7.x86_64 OSVersion="#1 SMP Thu Oct 29 17:29:29 EDT 2015" HostName=localhost.localdomain Architecture=x86_64
+Topology infos: Backend=Linux OSName=Linux OSRelease=3.10.0-327.el7.x86_64 OSVersion="#1 SMP Thu Oct 29 17:29:29 EDT 2015" HostName=localhost.localdomain Architecture=x86_64 MemoryTiersNr=2
 Topology not from this system

tests/hwloc/linux/fakeheteromemtiers.console

@@ -88,5 +88,5 @@ Memory attribute #5 name `WriteBandwidth' flags 5
   NUMANode L#4 = 100 from cpuset 0x0000000c (Group0 L#1)
   NUMANode L#1 = 100 from cpuset 0x00000003 (Group0 L#0)
   NUMANode L#6 = 100 from cpuset 0x00000030 (Group0 L#2)
-Topology infos: LinuxCgroup=/ Backend=Linux OSName=Linux OSRelease=5.18.0-rc4 OSVersion="#1 SMP PREEMPT_DYNAMIC Tue Apr 26 11:49:51 CEST 2022" HostName=efi Architecture=x86_64
+Topology infos: LinuxCgroup=/ Backend=Linux OSName=Linux OSRelease=5.18.0-rc4 OSVersion="#1 SMP PREEMPT_DYNAMIC Tue Apr 26 11:49:51 CEST 2022" HostName=efi Architecture=x86_64 MemoryTiersNr=3
 Topology not from this system

tests/hwloc/linux/fakememinitiators-1np2c+1npp+gi.console

@@ -83,5 +83,5 @@ Memory attribute #7 name `WriteLatency' flags 6
   NUMANode L#3 = 26 from cpuset 0x0000000c (Group0 L#2)
   NUMANode L#4 = 26 from cpuset 0x000000c0 (Group0 L#3)
   NUMANode L#5 = 77 from cpuset 0x000000cc (Package L#1)
-Topology infos: LinuxCgroup=/ Backend=Linux
+Topology infos: LinuxCgroup=/ Backend=Linux MemoryTiersNr=2
 Topology not from this system

tests/hwloc/linux/nvidiagpunumanodes-kept.console

@@ -106,5 +106,5 @@ Relative latency matrix (name NUMALatency kind 5) between 8 NUMANodes (depth -3)
      1    80    80    80    80    80    10    80    80
      2    80    80    80    80    80    80    10    80
      3    80    80    80    80    80    80    80    10
-Topology infos: LinuxCgroup=/jjh Backend=Linux OSName=Linux OSRelease=4.14.0-49.el7a.bz1553205.page_fault_hang.ppc64le OSVersion="#1 SMP Fri Mar 30 12:06:11 CDT 2018" HostName=c685f8n02 Architecture=ppc64le
+Topology infos: LinuxCgroup=/jjh Backend=Linux OSName=Linux OSRelease=4.14.0-49.el7a.bz1553205.page_fault_hang.ppc64le OSVersion="#1 SMP Fri Mar 30 12:06:11 CDT 2018" HostName=c685f8n02 Architecture=ppc64le MemoryTiersNr=2
 Topology not from this system