Xen Project Developer & Design Summit

Xen has made strides in scaling network performance such that it can now saturate 10 Gbit/s NICs and more taking in account aggregate throughput in multi-queued host backends.

Grant usage, one of the main bottlenecks associated with paravirtualizated I/O, has seen a number of improvements in the past years. However, 100 Gbit/s network adapters beckon and 25 Gbit/s will replace current 10 Gbit/s adapters in short order. This will require us to revisit the datapath.

This presentation discusses ways of overcoming this bottleneck and we describe the work we have been doing in the area without compromising the current grant-based model. We discuss a number of topics in this talk, such as page recycling mechanisms, grants versus copying and trends in networking/drivers. Finally we pitch an optional grant-less model in a way that can be managed by adminstrators and is transparent to guests.