On Wed, Nov 25, 2020 at 05:20:41PM +0000, Daniel P. Berrangé wrote: > On Wed, Nov 25, 2020 at 05:00:20PM +0000, Daniel P. Berrangé wrote: > > On Wed, Nov 25, 2020 at 04:36:39PM +0000, Daniel P. Berrangé wrote: > > > On Wed, Nov 25, 2020 at 04:49:14PM +0100, Christian Ehrhardt wrote: > > > > I found that the same vol-download vs 127.0.0.1 gives the same results. > > > > That in turn makes it easier to gather results as we only need one system. > > > > > > Yep, that's useful, I'm able to reproduce this problem myself too > > > now. Will do some local tests and report back... > > > > Sigh, the problem is way too many reallocs, repeatedly growing and shrinking > > the buffer we use for I/O. > > > > I guess we never noticed this awfulness in the virsh console code it was > > copied from, as the data volumes are lower. > > > > Switching to a fixed size buffer makes it massively faster. I'll prep a > > patch asap. > > Actually, it is also important to have a bigger buffer. Using a 1 MB buffer > makes all the difference in throughput. I've sent two patches to improve the performance and managed to test vol-download with our ssh helper to beat netcat. I've not had a chance to test with tunnelled migration yet though, so if you want to try the patches with your migration test scenario, that'd be useful confirmation 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 :|
