Re: [Qemu-devel] [PATCH v11 14/15] rdma: introduce MIG_STATE_NONE and change MIG_STATE_SETUP state transition

[Paolo Bonzini]

Il 26/06/2013 16:09, Michael R. Hines ha scritto:
> *This requires some steps:*
> 1. First, maintain a new data structure: something like
>     "These memory ranges are 'being unpinned'" - block all potential writes
>     to these addresses until the unpinning completes.
> 2. Once the source unpin completes, send the asynchronous control
> channel message
>     to the other side for unpinning.
> 2. Mark the data structure and return and allow the migration to continue
>     with the next RDMA write.
> 3. Upon completion of the unpinning on the destination,
>     respond to the source that it was finished.
> 4. Source then clears the data structure for the successfully unpinned
> memory ranges.
> 5. At this point, one or more writes may (or may not) be blocking on the
>     unpinned memory areas and will poll the data structure and find that
>     the unpinning has completed.
> 6. Then issue the new writes and proceed as normal.
> 7. Repeat step 1.

After more discussion on IRC I think I understand this.  It's not
trivial, but not super-complex either...  it would really be nice to add
it to the protocol already in 1.6.

Paolo