On Mon, 2015-01-05 at 14:09 -0800, Andrew Morton wrote: > On Mon, 22 Dec 2014 16:06:02 +1100 Cyril Bur <cyril...@gmail.com> wrote: > > > When the hypervisor pauses a virtualised kernel the kernel will observe a > > jump > > in timebase, this can cause spurious messages from the softlockup detector. > > > > Whilst these messages are harmless, they are accompanied with a stack trace > > which causes undue concern and more problematically the stack trace in the > > guest has nothing to do with the observed problem and can only be > > misleading. > > > > Futhermore, on POWER8 this is completely avoidable with the introduction of > > the Virtual Time Base (VTB) register. > > Does this problem apply to other KVM implementations and to Xen? If > so, what would implementations of running_clock() for those look like? > If not, why not? Yes the problem should appear on other KVM implementations, not really sure about Xen but I don't see why the problem wouldn't crop up.
x86 do have a method for dealing with it in the softlockup detector, they've added a check in the softlockup using a paravirtualised clock where the guest can discover if it had been paused, Xen could be using too. It doesn't appear s390 do anything. Thanks, Cyril > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
