Re: [Xen-devel] Time stopped

[Steven Hand <Steven.Hand@xxxxxxxxxxxx>]

> On Fri, 2005-10-14 at 16:48 +0200, Stephan Böni wrote:
> > Just for your information. I have the same problem on my installation.
> > 
> Thanks for the feedback. I was wondering if I was the only one seeing
> it. 


So managed to reproduce (once!) and now perhaps one step further to 
solving it - basically the guest is /not/ to blame; Xen itself is 
not updating time correctly. In my instance it was out (i.e. time 
was running slower) by a factor of approximately 16 -- 20. 

I'm trying to reproduce again to get more details - but it'd be
helpful if folks could apply the below and, if they repro the 
problem: 

  (1) get serial console to Xen (i.e. hit 'Ctrl-A' three times) 
  (2) hit 'a' to dump the ac_timer queues and the scale info, 
  (3) post the results to the list 

cheers,

S.




diff -r bd3268de4145 xen/arch/x86/time.c
--- a/xen/arch/x86/time.c       Fri Oct 14 14:40:48 2005
+++ b/xen/arch/x86/time.c       Fri Oct 14 17:44:46 2005
@@ -133,6 +133,15 @@
     return product;
 }
 
+void print_scale(int cpu) 
+{
+    struct cpu_time *t = &cpu_time[cpu]; 
+    struct time_scale *s = &t->tsc_scale;
+
+    printk("CPU%d: scale->mul_frac = %x\n", cpu, s->mul_frac); 
+    printk("CPU%d: scale->shift    = %d\n", cpu, s->shift); 
+}
+
 void timer_interrupt(int irq, void *dev_id, struct cpu_user_regs *regs)
 {
     if ( timer_ack ) 
diff -r bd3268de4145 xen/common/ac_timer.c
--- a/xen/common/ac_timer.c     Fri Oct 14 14:40:48 2005
+++ b/xen/common/ac_timer.c     Fri Oct 14 17:44:46 2005
@@ -225,6 +225,7 @@
     spin_unlock_irq(&ac_timers[cpu].lock);
 }
 
+extern void print_scale(int cpu); 
 
 static void dump_timerq(unsigned char key)
 {
@@ -239,6 +240,7 @@
     for_each_online_cpu( i )
     {
         printk("CPU[%02d] ", i);
+        print_scale( i ); 
         spin_lock_irqsave(&ac_timers[i].lock, flags);
         for ( j = 1; j <= GET_HEAP_SIZE(ac_timers[i].heap); j++ )
         {

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