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D24927.1785322101.diff
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Index: sys/x86/x86/mp_x86.c
===================================================================
--- sys/x86/x86/mp_x86.c
+++ sys/x86/x86/mp_x86.c
@@ -760,6 +760,7 @@
}
}
+
/*
* Add a scheduling group, a group of logical processors sharing
* a particular cache (and, thus having an affinity), to the scheduling
@@ -822,12 +823,25 @@
node = topo_next_node(root, node);
continue;
}
+
+ /*
+ * skip empty nodes, because they missmatch above test
+ * in every case and lead to disabled PUs.
+ */
+ if ((root->type != TOPO_TYPE_SYSTEM) &&
+ (CPU_COUNT(&node->cpuset) == 0)) {
+ node = topo_next_node(root, node);
+ continue;
+ }
+
nchildren++;
node = topo_next_nonchild_node(root, node);
}
- cg_root->cg_child = smp_topo_alloc(nchildren);
cg_root->cg_children = nchildren;
+ if (nchildren == 0)
+ return;
+ cg_root->cg_child = smp_topo_alloc(nchildren);
/*
* Now find again the same cache nodes as above and recursively
@@ -843,6 +857,11 @@
node = topo_next_node(root, node);
continue;
}
+ if ((root->type != TOPO_TYPE_SYSTEM) &&
+ (CPU_COUNT(&node->cpuset) == 0)) {
+ node = topo_next_node(root, node);
+ continue;
+ }
cg_root->cg_child[i].cg_parent = cg_root;
x86topo_add_sched_group(node, &cg_root->cg_child[i]);
i++;
@@ -850,6 +869,50 @@
}
}
+/*
+ * evaluate minimal and maximal depths of a cpu_group tree
+ */
+static void
+x86topo_eval_depth(struct cpu_group *cg_root, uint32_t *depth_min, uint32_t *depth_max)
+{
+ *depth_max = 1;
+ if (cg_root->cg_children == 0)
+ *depth_min = 1;
+ else
+ *depth_min = -1;
+
+ for (uint32_t i = 0; i < cg_root->cg_children; i++)
+ {
+ uint32_t node_min;
+ uint32_t node_max;
+ x86topo_eval_depth(cg_root->cg_child + i, &node_min, &node_max);
+ if (node_min + 1 < *depth_min)
+ *depth_min = node_min + 1;
+ if (node_max + 1 > *depth_max)
+ *depth_max = node_max + 1;
+ }
+}
+
+/*
+ * flatten tree to given level. This is done by cutting children.
+ * currently children are allocated from static array in smp_topo_alloc,
+ * thus extra cleanup is not required
+ */
+static void
+x86topo_flatten(struct cpu_group *cg_root, uint32_t level)
+{
+ if (level <= 1)
+ {
+ cg_root->cg_children = 0;
+ cg_root->cg_child = 0;
+ }
+ else
+ {
+ for (uint32_t i = 0; i < cg_root->cg_children; i++)
+ x86topo_flatten(cg_root->cg_child + i, level - 1);
+ }
+}
+
/*
* Build the MI scheduling topology from the discovered hardware topology.
*/
@@ -857,12 +920,23 @@
cpu_topo(void)
{
struct cpu_group *cg_root;
+ uint32_t depth_min, depth_max;
if (mp_ncpus <= 1)
return (smp_topo_none());
cg_root = smp_topo_alloc(1);
x86topo_add_sched_group(&topo_root, cg_root);
+
+ /*
+ * flaten topology to maximal hierarchy to avoid
+ * unbalanced trees. Depth can vary, if lapics are
+ * disabled by tunable
+ */
+ x86topo_eval_depth(cg_root, &depth_min, &depth_max);
+ if ((depth_min >= 2) && (depth_max > depth_min))
+ x86topo_flatten(cg_root, depth_min);
+
return (cg_root);
}

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