On Fri, Jun 02, 2023 at 10:22:28AM +0100, Peter Maydell wrote: > On Fri, 2 Jun 2023 at 10:10, Daniel P. Berrangé <berra...@redhat.com> wrote: > > I suspect that the zstd logic takes a little bit longer in setup, > > which allows often allows the guest dirty workload to get ahead of > > it, resulting in a huge amount of data to transfer. Every now and > > then the compression code gets ahead of the workload and thus most > > data is zeros and skipped. > > > > IMHO this feels like just another example of compression being largely > > useless. The CPU overhead of compression can't keep up with the guest > > dirty workload, making the supposedly network bandwidth saving irrelevant. > > It seems a bit surprising if compression can't keep up with > a TCG guest workload, though...
The multifd code seems to be getting slower and slower through the migration. It peaks at 39 mbps, but degrades down to 4 mbps when i test it. I doubt that the aarch64 is specifically a problem, rather it is just affecting timing that exposes some migration issue. With 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 :|
