Re: Xen system skew MUCH worse than tsc skew (was RE: [Xen-devel] RE: [PATCH] record max stime skew (was RE: [PATCH] strictly increasing hvm guest time))

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

On 19/7/08 18:51, "Dan Magenheimer" <dan.magenheimer@xxxxxxxxxx> wrote:

> Would you expect system load to impact stime skew between
> processors (using hpet as a system timer)?  I can repeatably
> watch skew get worse when I am launching an hvm domain.  It is
> MUCH worse when the new domain is in its early stages of booting.
> CPU load on domain0 has little or no impact but I/O load
> on dom0 seems to make skew get worse.

Perhaps it makes a difference if it takes each CPU a bit longer to execute
the calibration function in softirq context? That could be delayed by long
hypercalls, for example (although long hypercalls should mostly be
preemptible).

 -- Keir



_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel