+// This global counter is used to allow multiple threads to stop the
+// timer temporarily with a stopTimer()/startTimer() pair. If
+// timer_enabled == 0 timer is enabled
+// timer_disabled == N, N > 0 timer is disabled by N threads
+// When timer_enabled makes a transition to 0, we enable the timer,
+// and when it makes a transition to non-0 we disable it.
+
+static StgWord timer_disabled;
+