Re: Negative time with ps

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

On Tue, Mar 22, 2005 at 11:42:26AM +0100, Quentin Garnier wrote:
> On Tue, Mar 22, 2005 at 10:29:27AM +0200, Martti Kuparinen wrote:
> > I'm getting weird output from domain0's ps command. Any ideas
> > what's causing this?
> 
> root         4  0.0 19.2    0 24700 ?? DK   Wed02PM -18516351:-27.18 
> [pagedaemon]
> root         5  0.0 19.2    0 24700 ?? DK   Wed02PM -18516350:-26.87 [ioflush]
> root         6  0.0 19.2    0 24700 ?? DK   Wed02PM -18516351:-27.70 
> [aiodoned]
> 
> It happens in domU, too.

Yes.
The clock code isn't perfect. Especially, it doesn't compensate for the
fact that clock interrupts don't run at exacltly hz, because of domain
scheduling, and also because xen will send extra interrupts from
time to time, when domain0 updates the master clock. This needs more work.
Now, I'm not sure if this can cause the process time to become negative.
BTW, it this seems to happen only for kernel threads.

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
--