diff -uNr a/xen/common/trace.c b/xen/common/trace.c
--- a/xen/common/trace.c	2008-06-01 13:51:38.000000000 +0100
+++ b/xen/common/trace.c	2008-08-05 13:29:04.518299605 +0100
@@ -58,6 +58,7 @@
 
 /* Number of records lost due to per-CPU trace buffer being full. */
 static DEFINE_PER_CPU(unsigned long, lost_records);
+static DEFINE_PER_CPU(unsigned long, lost_records_first_tsc);
 
 /* a flag recording whether initialization has been done */
 /* or more properly, if the tbuf subsystem is enabled right now */
@@ -354,22 +355,27 @@
                     NULL);
 }
 
-#define LOST_REC_SIZE 8
+#define LOST_REC_SIZE (4 + 8 + 16) /* header + tsc + sizeof(struct ed) */
 
 static inline int insert_lost_records(struct t_buf *buf)
 {
     struct {
         u32 lost_records;
-    } ed;
+        unsigned did:16, vid:16;
+        u64 first_tsc;
+    } __attribute__((packed)) ed;
 
+    ed.vid = current->vcpu_id;
+    ed.did = current->domain->domain_id;
     ed.lost_records = this_cpu(lost_records);
+    ed.first_tsc = this_cpu(lost_records_first_tsc);
 
     this_cpu(lost_records) = 0;
 
     return __insert_record(buf,
                            TRC_LOST_RECORDS,
                            sizeof(ed),
-                           0 /* !cycles */,
+                           1 /* cycles */,
                            LOST_REC_SIZE,
                            (unsigned char *)&ed);
 }
@@ -479,7 +485,8 @@
     /* Do we have enough space for everything? */
     if ( total_size > bytes_to_tail )
     {
-        this_cpu(lost_records)++;
+        if ( ++this_cpu(lost_records) == 1 )
+            this_cpu(lost_records_first_tsc)=(u64)get_cycles();
         local_irq_restore(flags);
         return;
     }