http://bugzilla.xensource.com/bugzilla/show_bug.cgi?id=1616
yunhong.jiang@xxxxxxxxx changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |ASSIGNED
------- Comment #2 from yunhong.jiang@xxxxxxxxx 2010-06-01 00:45 -------
For issue 2, CPU panic when running cpu offline, it should comes from the
periodic_timer.
When a CPU is pull down, cpu_disable_scheduler will remove the single shot
timer, but the periodic_timer is not migrated.
After the vcpu is scheduled on another pCPU later, and then schedule out from
that new pcpu, the stop_timer(&prev->periodic_timer) will try to access the
per_cpu strucutre, whic still poiting to the offlined CPU's per_cpu area and
will cause trouble. This should be caused by the per_cpu changes.
I try to migrate the periodic_timer also when cpu_disable_scheduler() and seems
it works. ï¼?comments the migration in cpu_disable_scheudler will trigger the
printk).
Seems on your side, the timer will always be triggered before schedule out?
--jyh
diff -r 96917cf25bf3 xen/common/schedule.c
--- a/xen/common/schedule.c Fri May 28 10:54:07 2010 +0100
+++ b/xen/common/schedule.c Tue Jun 01 15:35:21 2010 +0800
@@ -487,6 +487,15 @@ int cpu_disable_scheduler(unsigned int c
migrate_timer(&v->singleshot_timer, cpu_mig);
}
+/*
+ if ( v->periodic_timer.cpu == cpu )
+ {
+ int cpu_mig = first_cpu(c->cpu_valid);
+ if ( cpu_mig == cpu )
+ cpu_mig = next_cpu(cpu_mig, c->cpu_valid);
+ migrate_timer(&v->periodic_timer, cpu_mig);
+ }
+*/
if ( v->processor == cpu )
{
set_bit(_VPF_migrating, &v->pause_flags);
@@ -505,7 +514,10 @@ int cpu_disable_scheduler(unsigned int c
* all locks.
*/
if ( v->processor == cpu )
+ {
+ printk("we hit the EAGAIN here\n");
ret = -EAGAIN;
+ }
}
}
return ret;
@@ -1005,6 +1017,11 @@ static void schedule(void)
perfc_incr(sched_ctx);
+ if (prev->periodic_timer.cpu != smp_processor_id() &&
!cpu_online(prev->periodic_timer.cpu))
+ {
+ printk("I'm now at cpu %x, timer's cpu is %x\n", smp_processor_id(),
prev->periodic_timer.cpu);
+ }
+
stop_timer(&prev->periodic_timer);
/* Ensure that the domain has an up-to-date time base. */
--
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