Would anyone be so kind as to test the performance of TCP streams on Windows 2k8R2 guests of KVM virt servers?
virtio-win-1.6.3 was published to address a problem described as “low performance” on Win2k8 guests. Actual performance was not recorded in the bug report.
On my KVM servers, Windows 2k8R2 guests are able to send data at less than 4Mbps. I test this by using netcat on Windows and piping a file to its input. The receiving end of the transfer is an un-virtualized CentOS system. Transfer rate is measured by selecting the stream in iptraf while it is active.
UDP transfers, such as by CIFS, will send data at around 400Mbps.
TCP transfers from Windows 2012 or Windows 8 are not similarly affected.
The same driver for Win2k8 was published by Red Hat in virtio-win 1.6.3,
1.6.4, and 1.6.5.
Does anyone see TCP transfer rates from Win2k8R2 that don’t look ridiculously slow?