diff -r 7a73e3aeb224 tools/xentrace/formats
--- a/tools/xentrace/formats	Mon May 04 22:52:18 2009 +0100
+++ b/tools/xentrace/formats	Sat May 09 05:09:50 2009 -0400
@@ -3,6 +3,7 @@ 0x0001f001  CPU%(cpu)d  %(tsc)d (+%(relt
 0x0001f001  CPU%(cpu)d  %(tsc)d (+%(reltsc)8d)  lost_records      0x%(1)08x
 0x0001f002  CPU%(cpu)d  %(tsc)d (+%(reltsc)8d)  wrap_buffer       0x%(1)08x
 0x0001f003  CPU%(cpu)d  %(tsc)d (+%(reltsc)8d)  cpu_change        0x%(1)08x
+0x0001f004  CPU%(cpu)d  %(tsc)d (+%(reltsc)8d)  do_guest_irq    [ vector = 0x%(1)08x, count = 0x%(2)08x, tot_cycles = 0x%(3)08x, max_cycles = 0x%(4)08x ]
 
 0x00021011  CPU%(cpu)d  %(tsc)d (+%(reltsc)8d)  running_to_runnable [ dom:vcpu = 0x%(1)08x ]
 0x00021021  CPU%(cpu)d  %(tsc)d (+%(reltsc)8d)  running_to_blocked  [ dom:vcpu = 0x%(1)08x ]
diff -r 7a73e3aeb224 xen/arch/x86/irq.c
--- a/xen/arch/x86/irq.c	Mon May 04 22:52:18 2009 +0100
+++ b/xen/arch/x86/irq.c	Sat May 09 05:09:50 2009 -0400
@@ -16,6 +16,7 @@
 #include <xen/compat.h>
 #include <xen/iocap.h>
 #include <xen/iommu.h>
+#include <xen/trace.h>
 #include <asm/msi.h>
 #include <asm/current.h>
 #include <asm/flushtlb.h>
@@ -26,6 +27,16 @@ boolean_param("noirqbalance", opt_noirqb
 boolean_param("noirqbalance", opt_noirqbalance);
 
 irq_desc_t irq_desc[NR_VECTORS];
+
+typedef struct irq_desc_measure
+{
+    unsigned long max_cycles;
+    unsigned long tot_cycles;
+    unsigned long count;
+} irq_desc_measure_t;
+
+irq_desc_measure_t irq_desc_measure[NR_VECTORS];
+
 
 static DEFINE_SPINLOCK(vector_lock);
 int vector_irq[NR_VECTORS] __read_mostly = {
@@ -109,11 +120,33 @@ int assign_irq_vector(int irq)
     return vector;
 }
 
+static inline void trace_guest_irq(unsigned int vector, 
+        unsigned long tsc_in)
+{
+    if(tb_init_done)
+    {
+        irq_desc_measure_t *desc = &irq_desc_measure[vector];
+        long tsc_diff = (long)((unsigned long)get_cycles() - tsc_in);
+
+        if(unlikely(tsc_diff < 0))
+            return;
+        
+        desc->tot_cycles += tsc_diff;
+        if(tsc_diff > desc->max_cycles)
+            desc->max_cycles = tsc_diff;
+        desc->count++;
+        TRACE_4D(TRC_TRACE_GUEST_IRQ, vector,
+                 desc->count, desc->tot_cycles, desc->max_cycles);
+    }
+    return;
+}
+
 asmlinkage void do_IRQ(struct cpu_user_regs *regs)
 {
     unsigned int      vector = regs->entry_vector;
     irq_desc_t       *desc = &irq_desc[vector];
     struct irqaction *action;
+    __volatile__ unsigned long tsc_in;
 
     perfc_incr(irqs);
 
@@ -123,7 +156,10 @@ asmlinkage void do_IRQ(struct cpu_user_r
     if ( likely(desc->status & IRQ_GUEST) )
     {
         irq_enter();
+        if(tb_init_done)
+            tsc_in = (unsigned long)get_cycles();
         __do_IRQ_guest(vector);
+        trace_guest_irq(vector, tsc_in);
         irq_exit();
         spin_unlock(&desc->lock);
         return;
@@ -147,7 +183,10 @@ asmlinkage void do_IRQ(struct cpu_user_r
         desc->status &= ~IRQ_PENDING;
         irq_enter();
         spin_unlock_irq(&desc->lock);
+        if(tb_init_done)
+            tsc_in = (unsigned long)get_cycles();
         action->handler(vector_to_irq(vector), action->dev_id, regs);
+        trace_guest_irq(vector, tsc_in);
         spin_lock_irq(&desc->lock);
         irq_exit();
     }
diff -r 7a73e3aeb224 xen/include/public/trace.h
--- a/xen/include/public/trace.h	Mon May 04 22:52:18 2009 +0100
+++ b/xen/include/public/trace.h	Sat May 09 05:09:50 2009 -0400
@@ -59,6 +59,7 @@
 #define TRC_LOST_RECORDS        (TRC_GEN + 1)
 #define TRC_TRACE_WRAP_BUFFER  (TRC_GEN + 2)
 #define TRC_TRACE_CPU_CHANGE    (TRC_GEN + 3)
+#define TRC_TRACE_GUEST_IRQ     (TRC_GEN + 4)
 
 #define TRC_SCHED_RUNSTATE_CHANGE   (TRC_SCHED_MIN + 1)
 #define TRC_SCHED_CONTINUE_RUNNING  (TRC_SCHED_MIN + 2)