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 :|