[Qemu-devel] Re: [PATCH] qemu-kvm: introduce cpu_start/cpu_stop commands

[Chris Wright]

* Anthony Liguori (address@hidden) wrote:
> On 11/22/2010 05:04 PM, Chris Wright wrote:
> >* Anthony Liguori (address@hidden) wrote:
> >>qemu-kvm vcpu threads don't response to SIGSTOP/SIGCONT.  Instead of 
> >>teaching
> >>them to respond to these signals, introduce monitor commands that stop and 
> >>start
> >>individual vcpus.
> >In the past SIGSTOP has introduced time skew.  Have you verified this
> >isn't an issue.
> 
> Time skew is a big topic.  Are you talking about TSC drift,
> pit/rtc/hpet drift, etc?

Sorry to be vague, but it's been long enough that I don't recall
the details.  The guest kernel's clocksource effected how timekeeping
progressed across STOP/CONT (was probably missing qemu based timer ticks).
While this is not the same, made me wonder if you'd tested against that.

> It's certainly going to stress periodic interrupt catch up code.

Heh, call it a feature for autotest ;)

thanks,
-chris