On Thu, Feb 27, 2014 at 03:17:44PM +0100, Stefan Hajnoczi wrote: > On Mon, Feb 24, 2014 at 05:14:04PM +0100, Luke Gorrie wrote: > > On 24 February 2014 16:20, Stefan Hajnoczi <stefa...@gmail.com> wrote: > > > > > Do you want the 1:1 mapping to achieve best performance or just to > > > simplify the coding? > > > > > > > We want to keep the real-time constraints on the data plane comfortable. > > > > The question I ask myself is: How long can I buffer packets during > > processing before something is dropped? > > > > 256 buffers can be consumed in 17 microseconds on a 10G interface. > > This is a good point. The virtio-net vring is too small at 256 buffers > for workloads that want to send/receive small packets at 10 Gbit/s line > rate. (Minimum UDP packet size is 52 bytes!) > > Michael: Luke has asked to increase the virtio-net virtqueue size. > Thoughts? > > Stefan
Heh you want to increase the bufferbloat? Each buffer pointer takes up 16 bytes so we are using order-2 allocations as it is, anything more and it'll start to fail if hotplug happens long after boot. AFAIK baremetal does not push line rate with 1 byte payload either. -- MST
