diff -r 77dec8732cde xen/common/trace.c
--- a/xen/common/trace.c	Wed Apr 23 16:58:44 2008 +0100
+++ b/xen/common/trace.c	Thu Apr 24 15:56:37 2008 +0900
@@ -69,6 +69,13 @@ static cpumask_t tb_cpu_mask = CPU_MASK_
 /* which tracing events are enabled */
 static u32 tb_event_mask = TRC_ALL;
 
+static void trace_notify_guest(unsigned long unused)
+{
+    send_guest_global_virq(dom0, VIRQ_TBUF);
+}
+
+static DECLARE_TASKLET(trace_tasklet, trace_notify_guest, 0);
+
 /**
  * alloc_trace_bufs - performs initialization of the per-cpu trace buffers.
  *
@@ -506,7 +513,7 @@ void __trace_var(u32 event, int cycles, 
     /* Notify trace buffer consumer that we've crossed the high water mark. */
     if ( started_below_highwater &&
          (calc_unconsumed_bytes(buf) >= t_buf_highwater) )
-        send_guest_global_virq(dom0, VIRQ_TBUF);
+        tasklet_schedule(&trace_tasklet);
 }
 
 /*