[Xen-devel] RE: PV resume failed after self migration failed

[MaoXiaoyun <tinnycloud@xxxxxxxxxxx>]

 

> Subject: RE: PV resume failed after self migration failed
> Date: Fri, 17 Jun 2011 11:34:09 +1000
> From: james.harper@xxxxxxxxxxxxxxxx
> To: tinnycloud@xxxxxxxxxxx; xen-devel@xxxxxxxxxxxxxxxxxxx
>
> > Hi James:
> >
> > I found another issue during test.
> > When migrating VM from host A to B, it contains following process.
> > 1) memory copy
> > 2) suspend VM on A
> > 3) transfer some other thing to B such as tsc state.
> >
> > If step (3) failed, VM will be resumed on host A.
> > Well, from the test of view, the resume cannot be completed
> successfully.
> >
> > Out test is migrating 12VMs between twn host over again and again.
> > The attached log doing exactly below things
> > 1) Migrate from Host B, so fisrt resuming (line 25 to 474)
> > 2) Later want to migrating to B again, so suspending (line 474 to
> line
> > 1116)
> > 3) Migrating failed and enter into resuming again (line 1118 to
> line
> > 1399).
> >
> > line 1383 is waiting vbd state to be changed but can not get the
> > response.
> > And 1392 show a "Unacknowledged event word ". From the log, it looks
> like
> > this is due to XenVbd_HwScsiResetBus in line 1397.
> >
> > Question is what trigger the XenVbd_HwScsiResetBus during
> resuming?
> >
>
> Windows will invoke a scsi reset if a request takes too long to complete
> (5 seconds I think). It will also issue a reset when a crash dump
> starts, just to make sure all previous requests are flushed etc.
>

Thanks for the help, sorry for the late response, I've been leaving a while lase weekend.
 
If VBD is already suspended, all further IO try to issue will find vbd states is not SR_STATE_RUNNING,
thus calls ScsiPortNotification to notify RequestComplete, right?
 
If so, I have an assumption.
at time t, VBD is suspend, an IO is try to issue, but before it calls ScsiPortNotificaiton, the whole
VM paused(VCPU paused, last step of step),  10 or more seconds later, if VM resumes,  will the driver
found the IO mentioned before has already timed out and trigger XenVbd_HwScsiResetBus?
 
 
 
thanks.

> James

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