On Wed, Apr 24, 2019 at 11:30:39AM -0700, Paul E. McKenney wrote:
> On Wed, Apr 24, 2019 at 03:38:09AM -0700, Paul E. McKenney wrote:
> > On Wed, Apr 24, 2019 at 09:34:46AM +0200, Sebastian Andrzej Siewior wrote:
> > > In one of my rcutorture tests the TSC clocksource got marked unstable
> > > due to a large difference in the TSC value. I'm not sure if the guest
> > > run for a long time with disabled interrupts or if the host was very
> > > busy and didn't schedule the guest for some time.
> > > I took a look on the qemu/KVM options and decided to update the options:
> > > - Use kvm{32|64} as CPU. We could probably use `host' (like ARM does)
> > > for maximum available features but since we don't run any userland I'm
> > > not sure if it makes any difference.
> > >
> > > - Drop the "noapic" option, enable TSC deadline timer. There is no
> > > history why the APIC was disabled, I see no reason for it. The
> > > deadline timer is probably "nicer".
> > >
> > > - Additional config options. It ensures that the kernel knowns that it
> > > runs as a kvm guest and can use virt devices like the kvm-clock as
> > > clocksource. The kvm-clock was the main motivation here.
> > >
> > > - I didn't add a random HW device. It would make the random device ready
> > > earlier (not it doesn't complete the initialisation at all) but I
> > > doubt that there is any need for this.
> > >
> > > Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
> >
> > Thank you, Sebastian! Queued for review and testing.
>
> And it doesn't like my (admittedly ancient) QEMU, complaining about not
> knowing about "x2apic=on,tsc-deadline=on,hypervisor=on,tsc_adjust=on".
> If I remove these, it works. I will be upgrading soon (famous last
> words), so what I am going to do is queue the following separate
> not-for-upstream patch that makes it work on my setup.
Also, the !SMP scenarios get this:
:CONFIG_PARAVIRT_SPINLOCKS=y: improperly set
Would it make sense to only set this on CONFIG_SMP=y runs? The easy
way to do this is to move it from CFcommon to the scenario files not
having CONFIG_SMP=n. Or would something else work better?
Or am I doing something wrong?
Thanx, Paul
