linux/numa: disable memory attributes and memory-side cache in fake numa

HMAT information isn't updated when fake numa is enabled,
so ignore it for now.

In the uniform splitting fake numa case, we could update HMAT info
since node #K is replaced with nodes #KN-#(K+1)N-1.
In theory, the Linux kernel should fix HMAT info to match the
fakenuma config, but it looks like it's not going to happen soon,
we'll see later if we need/want to fix it in hwloc.

Signed-off-by: Brice Goglin <[email protected]>

Author: bgoglin

hwloc/topology-linux.c

@@ -3975,9 +3975,18 @@ look_sysfsnode(struct hwloc_topology *topology,
   char *env;
   int allow_overlapping_node_cpusets = 0;
   int need_memcaches = hwloc_filter_check_keep_object_type(topology, HWLOC_OBJ_MEMCACHE);
+  int need_memattrs = !(topology->flags & HWLOC_TOPOLOGY_FLAG_NO_MEMATTRS);
 
   hwloc_debug("\n\n * Topology extraction from /sys/devices/system/node *\n\n");
 
+  if (data->is_fake_numa_uniform) {
+    hwloc_debug("Disabling memory-side caches, memory attributes and HMAT initiators because of fake numa\n");
+    need_memcaches = 0;
+    need_memattrs = 0;
+    data->use_numa_initiators = 0;
+    allow_overlapping_node_cpusets = 2; /* accept without warning */
+  }
+
   env = getenv("HWLOC_DEBUG_ALLOW_OVERLAPPING_NODE_CPUSETS");
   if (env) {
     allow_overlapping_node_cpusets = atoi(env); /* 0 drop non-first overlapping nodes, 1 allows with warning, 2 allows without warning */
@@ -4183,7 +4192,7 @@ look_sysfsnode(struct hwloc_topology *topology,
 	  trees[nr_trees++] = tree;
 	}
         /* By the way, get their memattrs now that cpuset is fixed */
-        if (!(topology->flags & HWLOC_TOPOLOGY_FLAG_NO_MEMATTRS))
+        if (need_memattrs)
           read_node_local_memattrs(topology, data, node);
       }