[libvirt] [PATCH] virnuma: Check for numa_bitmask_isbitset presence

4 Jun 2014

On some systems, libnuma can be present but it's so ancient that
it misses some symbols that virNumaGetDistances() needs. To be
more precise: numa_bitmask_isbitset() and numa_nodes_ptr are the
symbols in question. Fortunately, they were both introduced in
the same release so it's sufficient for us to check for only one
of them. And the winner is numa_bitmask_isbitset().

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
---

Notes:
    While this is a build breaker, it's not that critical. Come on -
    who runs libvirt from git on stable enterprise systems? I'm
    sending it to know if the check for numa_bitmask_isbitset() is in
    the right place or should be moved to a different file.

 m4/virt-numactl.m4 |   4 ++
 src/util/virnuma.c | 135 +++++++++++++++++++++++++++--------------------------
 2 files changed, 73 insertions(+), 66 deletions(-)

diff --git a/m4/virt-numactl.m4 b/m4/virt-numactl.m4
index 1dcb029..fa66d24 100644
--- a/m4/virt-numactl.m4
+++ b/m4/virt-numactl.m4
@@ -19,6 +19,10 @@ dnl
 
 AC_DEFUN([LIBVIRT_CHECK_NUMACTL],[
   LIBVIRT_CHECK_LIB([NUMACTL], [numa], [numa_available], [numa.h])
+  AC_CHECK_LIB([numa], [numa_bitmask_isbitset], [have_numa_bitmask_isbitset=yes])
+  if test "$have_numa_bitmask_isbitset" = "yes"; then
+    AC_DEFINE_UNQUOTED([HAVE_NUMA_BITMASK_ISBITSET], 1, [whether numa_bitmask_isbitset is available])
+  fi
 ])
 
 AC_DEFUN([LIBVIRT_RESULT_NUMACTL],[
diff --git a/src/util/virnuma.c b/src/util/virnuma.c
index 042844b..f979f49 100644
--- a/src/util/virnuma.c
+++ b/src/util/virnuma.c
@@ -217,61 +217,6 @@ virNumaGetMaxNode(void)
 
 
 /**
- * virNumaGetDistances:
- * @node: identifier of the requested NUMA node
- * @distances: array of distances to sibling nodes
- * @ndistances: size of @distances
- *
- * Get array of distances to sibling nodes from @node. If a
- * distances[x] equals to zero, the node x is not enabled or
- * doesn't exist. As a special case, if @node itself refers to
- * disabled or nonexistent NUMA node, then @distances and
- * @ndistances are set to NULL and zero respectively.
- *
- * The distances are a bit of magic. For a local node the value
- * is 10, for remote it's typically 20 meaning that time penalty
- * for accessing a remote node is two time bigger than when
- * accessing a local node.
- *
- * Returns 0 on success, -1 otherwise.
- */
-int
-virNumaGetDistances(int node,
-                    int **distances,
-                    int *ndistances)
-{
-    int ret = -1;
-    int max_node;
-    size_t i;
-
-    if (!numa_bitmask_isbitset(numa_nodes_ptr, node)) {
-        VIR_DEBUG("Node %d does not exist", node);
-        *distances = NULL;
-        *ndistances = 0;
-        return 0;
-    }
-
-    if ((max_node = virNumaGetMaxNode()) < 0)
-        goto cleanup;
-
-    if (VIR_ALLOC_N(*distances, max_node) < 0)
-        goto cleanup;
-
-    *ndistances = max_node + 1;
-
-    for (i = 0; i<= max_node; i++) {
-        if (!numa_bitmask_isbitset(numa_nodes_ptr, i))
-            continue;
-
-        (*distances)[i] = numa_distance(node, i);
-    }
-
-    ret = 0;
- cleanup:
-    return ret;
-}
-
-/**
  * virNumaGetNodeMemory:
  * @node: identifier of the requested NUMA node
  * @memsize: returns the total size of memory in the NUMA node
@@ -443,17 +388,6 @@ virNumaGetNodeCPUs(int node ATTRIBUTE_UNUSED,
                    _("NUMA isn't available on this host"));
     return -1;
 }
-
-int
-virNumaGetDistances(int node ATTRIBUTE_UNUSED,
-                    int **distances,
-                    int *ndistances)
-{
-    *distances = NULL;
-    *ndistances = 0;
-    VIR_DEBUG("NUMA isn't available on this host");
-    return 0;
-}
 #endif
 
 
@@ -469,3 +403,72 @@ virNumaGetMaxCPUs(void)
 {
     return NUMA_MAX_N_CPUS;
 }
+
+
+#ifdef HAVE_NUMA_BITMASK_ISBITSET
+/**
+ * virNumaGetDistances:
+ * @node: identifier of the requested NUMA node
+ * @distances: array of distances to sibling nodes
+ * @ndistances: size of @distances
+ *
+ * Get array of distances to sibling nodes from @node. If a
+ * distances[x] equals to zero, the node x is not enabled or
+ * doesn't exist. As a special case, if @node itself refers to
+ * disabled or nonexistent NUMA node, then @distances and
+ * @ndistances are set to NULL and zero respectively.
+ *
+ * The distances are a bit of magic. For a local node the value
+ * is 10, for remote it's typically 20 meaning that time penalty
+ * for accessing a remote node is two time bigger than when
+ * accessing a local node.
+ *
+ * Returns 0 on success, -1 otherwise.
+ */
+int
+virNumaGetDistances(int node,
+                    int **distances,
+                    int *ndistances)
+{
+    int ret = -1;
+    int max_node;
+    size_t i;
+
+    if (!numa_bitmask_isbitset(numa_nodes_ptr, node)) {
+        VIR_DEBUG("Node %d does not exist", node);
+        *distances = NULL;
+        *ndistances = 0;
+        return 0;
+    }
+
+    if ((max_node = virNumaGetMaxNode()) < 0)
+        goto cleanup;
+
+    if (VIR_ALLOC_N(*distances, max_node) < 0)
+        goto cleanup;
+
+    *ndistances = max_node + 1;
+
+    for (i = 0; i<= max_node; i++) {
+        if (!numa_bitmask_isbitset(numa_nodes_ptr, i))
+            continue;
+
+        (*distances)[i] = numa_distance(node, i);
+    }
+
+    ret = 0;
+ cleanup:
+    return ret;
+}
+#else
+int
+virNumaGetDistances(int node ATTRIBUTE_UNUSED,
+                    int **distances,
+                    int *ndistances)
+{
+    *distances = NULL;
+    *ndistances = 0;
+    VIR_DEBUG("NUMA isn't available on this host");
+    return 0;
+}
+#endif
-- 
2.0.0

    

Michal Privoznik

Daniel P. Berrange

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