Re: 2.6.35-rc1 regression with pvclock and smp guests

Avi Kivity
2010-07-27T12:06:34Z

On 07/27/2010 02:49 PM, Andre Przywara wrote:
>
>> What is the guest executing when it hangs?
> Both VCPUs are halted, the monitor and System.map tell me it's in
> native_safe_halt().
> The code sequence confirms this, it is an intentional sti;hlt condition.
> Using -smp 16 also shows that all 16 VCPUs are stuck.
>

Well, strange. The intent of that patch was to make the clock never go
backwards. Perhaps the change made it go forwards by a large amount,
and the guest is not hung, just waiting for some timer that is far in
the future.

Can you do something like

- if (ret < last)
+ if (ret < last) {
+ static u64 max_delta;
+ if (last - ret > max_delta) {
+ max_delta = last - ret;
+ printk("advancing kvmclock by: %llx\n", max_delta);
+ }
return last;
+ }

to see if this is happening?

--
error compiling committee.c: too many arguments to function