Subject: Re: LFS and Xen3 testing
To: Jed Davis <>
From: Manuel Bouyer <>
List: current-users
Date: 09/13/2006 22:01:31
On Tue, Sep 12, 2006 at 07:32:48PM -0400, Jed Davis wrote:
> (YAMAMOTO Takashi) writes:
> >> I've just recently discovered something interesting with Xen3 that
> >> might be related: if the dom0 is running something that spins the CPU
> >> (like "perl -e '1 while 1'" or "yes > /dev/null") the NetBSD domU will
> >> not be run at all; it won't respond to the console nor to network
> >> traffic, and its timer event handler won't be called.  A Linux domU
> >> doesn't appear to have the same problem.
> >
> > it's a characteristic of the default setting of sedf scheduler.
> > are you sure it doesn't happen for linux domU?
> The Linux domU is definitely affected, but it's still able to answer
> pings (if a bit slowly), while the NetBSD one doesn't answer any until
> the dom0 stops hogging the CPU.
> However, I see what you mean about the default scheduling parameters,
> I think -- giving the domU a nonzero minimum timeslice fixes this.

Maybe it's a hard interrupts vs soft interrupt issue ? E.g. hard interrupts
still running but soft interrupts not running when no time is allocated
to the domU ?

Manuel Bouyer <>
     NetBSD: 26 ans d'experience feront toujours la difference