Re: I/O errors in guest OS after repeated migration

[Guido Winkelmann <guido-kvml@thisisnotatest.de>]

Am Montag, 29. Oktober 2012, 12:29:01 schrieb Stefan Hajnoczi:
> On Fri, Oct 19, 2012 at 2:55 PM, Guido Winkelmann
> <guido-kvml@thisisnotatest.de> wrote:
> > Am Donnerstag, 18. Oktober 2012, 18:05:39 schrieb Avi Kivity:
> >> On 10/18/2012 05:50 PM, Guido Winkelmann wrote:
> >> > Am Mittwoch, 17. Oktober 2012, 13:25:45 schrieb Brian Jackson:
> >> >> 
> >> >> What about newer versions of qemu/kvm? But of course if those work,
> >> >> your
> >> >> next task is going to be git bisect it or file a bug with your distro
> >> >> that
> >> >> is using an ancient version of qemu/kvm.
> >> > 
> >> > I've just upgraded both hosts to qemu-kvm 1.2.0
> >> > (qemu-1.2.0-14.fc17.x86_64,
> >> > built from spec files under
> >> > http://pkgs.fedoraproject.org/cgit/qemu.git/).
> >> > 
> >> > The bug is still there.
> >> 
> >> If you let the guest go idle (no I/O), then migrate it, then restart the
> >> I/O, do the errors show?
> > 
> > Just tested - yes, they do.
> 
> The -EIO error does not really reveal why there is a problem.  You can
> use SystemTap probes in QEMU to find out more about the nature of the
> error.
> 
> # stap -e 'probe qemu.kvm.bdrv_*, qemu.kvm.virtio_blk_*,
> qemu.kvm.paio_* { printf("%s(%s)\n", probefunc(), $$parms) }' -x
> $PID_OF_QEMU

This does not work for me. When I try running this, I'm getting many pages of 
errors like this:

======
# stap -e 'probe qemu.kvm.bdrv_*, qemu.kvm.virtio_blk_*, qemu.kvm.paio_* { 
printf("%s(%s)\n", probefunc(), $$parms) }' -x 1623
parse error: expected statement
        saw: keyword at /usr/share/systemtap/tapset/qemu-alpha.stp:1455:3
     source:   function = $arg3;
               ^
parse error: expected identifier
        saw: operator '=' at /usr/share/systemtap/tapset/qemu-
alpha.stp:1455:12
     source:   function = $arg3;
                        ^
2 parse errors.
======

Unfortunately, I don't know the first thing about systemtap, so I don't really 
know what's happening here...

	Guido