clarified signature: more concise operations;

--- a/src/Pure/System/numa.scala	Mon Feb 20 17:13:19 2023 +0100
+++ b/src/Pure/System/numa.scala	Mon Feb 20 21:04:49 2023 +0100
@@ -37,19 +37,27 @@
   def policy(node: Int): String =
     if (numactl_available) "numactl -m" + node + " -N" + node else ""
 
-  def policy_options(options: Options, numa_node: Option[Int] = Some(0)): Options =
+  def policy_options(options: Options, numa_node: Option[Int]): Options =
     numa_node match {
       case None => options
       case Some(n) => options.string("ML_process_policy") = policy(n)
     }
 
+  def perhaps_policy_options(options: Options): Options = {
+    val numa_node =
+      try {
+        nodes() match {
+          case ns if ns.length >= 2 && numactl_available => ns.headOption
+          case _ => None
+        }
+      }
+      catch { case ERROR(_) => None }
+    policy_options(options, numa_node)
+  }
+
 
   /* shuffling of CPU nodes */
 
-  def available: Boolean =
-    try { nodes().length >= 2 && numactl_available }
-    catch { case ERROR(_) => false }
-
   def enabled_warning(progress: Progress, enabled: Boolean): Boolean = {
     def warning =
       if (nodes().length < 2) Some("no NUMA nodes available")

--- a/src/Pure/Tools/dump.scala	Mon Feb 20 17:13:19 2023 +0100
+++ b/src/Pure/Tools/dump.scala	Mon Feb 20 21:04:49 2023 +0100
@@ -97,9 +97,8 @@
       skip_base: Boolean = false
     ): Context = {
       val session_options: Options = {
-        val options0 = if (NUMA.available) NUMA.policy_options(options) else options
         val options1 =
-          options0 +
+          NUMA.perhaps_policy_options(options) +
             "parallel_proofs=0" +
             "completion_limit=0" +
             "editor_tracing_messages=0"