Re: Low throughput in VMs using VxLAN

On 08/24/2015 09:19 AM, Santosh R wrote:

  Hi,

    Earlier I was seeing lower throughput in VMs using VxLan as GRO was
not happening in VM.
Tom Herbert suggested to use "vxlan: GRO support at tunnel layer" patch series.
With today's net-next (4.2.0-rc7) in host and VM, I could see GRO
happening for vxlan, macvtap and virtual interface in VM.
The throughput is still low between VMs (around 4Gbps compared to
9Gbps without VxLAN).

Out of curiosity, have you tried tweaking gro_flush_timeout 
(gro_flush_interval?) for the VMs eth interface?  Say perhaps a value of 
1000?  (I'm assuming the VM is using virtio_net) Does the behaviour 
change if vhost-net is loaded into the host and used by the VM?

rick jones

For completeness, it would also be good to compare the likes of netperf 
TCP_RR between VxLAN and without.