Re: [kvm-devel] [PATCH 0/4] paravirt clock patches

[Gerd H. <kr...@re...>]

Marcelo Tosatti wrote:
> On Thu, Apr 24, 2008 at 10:37:04AM +0200, Gerd Hoffmann wrote:
>>   Hi folks,
>>
>> My first attempt to send out a patch series with git ...
>>
>> The patches fix the kvm paravirt clocksource code to be compatible with
>> xen and they also factor out some code which can be shared into a
>> separate source files used by both kvm and xen.
> 
> The issue with SMP guests is still present. Booting with "nohz=off" resolves it.
> 
> Same symptoms as before, apic_timer_fn for one of the vcpu's is ticking way slower
> than the remaining ones:
> 
> [root@localhost ~]# cat /proc/timer_stats  | grep apic
>   391,  4125 qemu-system-x86  apic_mmio_write (apic_timer_fn)
>  2103,  4126 qemu-system-x86  apic_mmio_write (apic_timer_fn)
>  1896,  4127 qemu-system-x86  apic_mmio_write (apic_timer_fn)
>  1857,  4128 qemu-system-x86  apic_mmio_write (apic_timer_fn)

What userspace version is this?  With iothread support?  Or older one
where the vcpu0 thread also handles all the I/O?  Is 4x neeed to
reproduce or do you see it with 2x too?  What host?

A quick test with xenner (which has a separate I/O thread) didn't show
anything unusual.  Going investigate ...

cheers,
  Gerd

-- 
http://kraxel.fedorapeople.org/xenner/