On Thu, Apr 12, 2018 at 4:28 PM, Daniel P. Berrangé <berra...@redhat.com> wrote: > On Wed, Apr 11, 2018 at 06:18:18PM +0100, Dr. David Alan Gilbert wrote: >> * Lidong Chen (jemmy858...@gmail.com) wrote: >> > The default get_return_path function of iochannel does not work for >> > RDMA live migration. So add the interface to set get_return_path. >> > >> > Signed-off-by: Lidong Chen <lidongc...@tencent.com> >> >> Lets see how Dan wants this done, he knows the channel/file stuff; >> to me this feels like it should be adding a member to QIOChannelClass >> that gets used by QEMUFile's get_return_path. > > No that doesn't really fit the model. IMHO the entire concept of a separate > return path object is really wrong. The QIOChannel implementations are > (almost) all capable of bi-directional I/O, which is why the the > get_retun_path > function just creates a second QEMUFile pointing to the same QIOChannel > object we already had. Migration only needs the second QEMUFile, because that > struct re-uses the same struct fields for tracking different bits of info > depending on which direction you're doing I/O in. A real fix would be to > stop overloading the same fields for multiple purposes in the QEMUFile, so > that we only needed a single QEMUFile instance. > > Ignoring that though, the particular problem we're facing here is that the > QIOChannelRDMA impl that is used is not written in a way that allows > bi-directional I/O, despite the RDMA code it uses being capable of it. > > So rather than changing this get_return_path code, IMHO, the right fix to > simply improve the QIOChannelRDMA impl so that it fully supports > bi-directional > I/O like all the other channels do.
Hi Daniel: Thanks for your suggestion. I will have a try. > > Regards, > Daniel > -- > |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| > |: https://libvirt.org -o- https://fstop138.berrange.com :| > |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|