Re: [libvirt] qemu-kvm-0.10.5, kvm-kmod-2.6.30, libvirt-0.6.4 -save/restore still unreliable

Nikola Ciprich
2009-06-16T20:35:45Z

Hello Charles,

> Otherwise -- at the monitor, migrate "exec:cat >somefile.out"
I tried that, saving seems to work OK,

but if I restore the domain, kvm always seems to be stuck, I'm not able to swith
to monitor to do anything. running strace on the kvm process show that
following is repeating:

clock_gettime(CLOCK_MONOTONIC, {453254, 437209647}) = 0
clock_gettime(CLOCK_MONOTONIC, {453254, 437244463}) = 0
clock_gettime(CLOCK_MONOTONIC, {453254, 437295938}) = 0
select(20, [5 10 17 19], [], [], {1, 0}) = 1 (in [5], left {0, 999998})
read(5, "\0", 512) = 1
read(5, 0x7fff60506840, 512) = -1 EAGAIN (Resource temporarily unavailable)
clock_gettime(CLOCK_MONOTONIC, {453254, 437458602}) = 0
clock_gettime(CLOCK_MONOTONIC, {453254, 437492440}) = 0
timer_gettime(0, {it_interval={0, 0}, it_value={0, 0}}) = 0
timer_settime(0, 0, {it_interval={0, 0}, it_value={0, 30000000}}, NULL) = 0
clock_gettime(CLOCK_MONOTONIC, {453254, 437605596}) = 0
clock_gettime(CLOCK_MONOTONIC, {453254, 437639489}) = 0
select(20, [5 10 17 19], [], [], {1, 0}) = 1 (in [19], left {0, 970104})
read(19, "\16\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 128) = 128
rt_sigaction(SIGALRM, NULL, {0x4083b0, ~[KILL STOP RTMIN RT_1], SA_RESTORER, 0x7f25576e94c0}, 8) = 0
write(6, "\0", 1) = 1
read(19, 0x7fff605069c0, 128) = -1 EAGAIN (Resource temporarily unavailable)

I guess I maybe need to unfreeze the domain somehow after loading it?

>
> Replace cat with gzip -c or other compression tool (and reverse on
> migrate in) for more efficient on-disk storage.
>
> -----Original Message-----
> From: Nikola Ciprich [mailto:extmaillist@linuxbox.cz]
> Sent: Saturday, June 13, 2009 1:32 AM
> To: CHARLESDUFFY
> Cc: kvm@vger.kernel.org; nikola.ciprich@linuxbox.cz
> Subject: Re: [libvirt] qemu-kvm-0.10.5, kvm-kmod-2.6.30, libvirt-0.6.4
> -save/restore still unreliable
>
> Hmm,
> I just noticed that dump file saved using virsh contains some libvirt
> related headers, so I guess I can't just feed it directly to qemu-kvm.
> So I guess best way to test save/restore without libvirt is to save
> vm state using monitor and then restore it again.
> But I can't find any clear documentation on how to do this.
> Could anyone give me a hint?
> thanks a lot!
> nik
>
>
> On Fri, Jun 12, 2009 at 03:17:18PM -0500, Charles Duffy wrote:
> > That may well be a guest issue rather than a qemu migration problem --
>
> > I've seen similar difficulties for guests being resumed via incoming
> > migration when using guest kernels with TSC as their clocksource.
> >
> > You might try interrogating the monitor to see your guest's state.
> >
> > --
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> >
>
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