Re: Question on skip_emulated_instructions()

[Avi Kivity <avi@redhat.com>]

On 04/08/2010 11:30 AM, Yoshiaki Tamura wrote:
>
> If I transferred a VM after I/O operations, let's say the VM sent an 
> TCP ACK to the client, and if a hardware failure occurred to the 
> primary during the VM transferring *but the client received the TCP 
> ACK*, the secondary will resume from the previous state, and it may 
> need to receive some data from the client. However, because the client 
> has already receiver TCP　ACK, it won't resend the data to the 
> secondary.  It looks this data is going to be dropped.  Am I missing 
> some point here?
>

I think you should block I/O not at the cpu/device boundary (that's 
inefficient as many cpu I/O instructions don't necessarily cause 
externally visible I/O) but at the device level.  Whenever the network 
device wants to send out a packet, halt the guest (letting any I/O 
instructions complete), synchronize the secondary, and then release the 
pending I/O.  This ensures that the secondary has all of the data prior 
to the ack being sent out.

-- 
error compiling committee.c: too many arguments to function