On 10/31/2017 03:07 AM, Wei Xu wrote:

On Thu, Oct 26, 2017 at 01:53:12PM -0400, Matthew Rosato wrote:

quoted

quoted

Are you using the same binding as mentioned in previous mail sent by you? it
might be caused by cpu convention between pktgen and vhost, could you please
try to run pktgen from another idle cpu by adjusting the binding? 

I don't think that's the case -- I can cause pktgen to hang in the guest
without any cpu binding, and with vhost disabled even.

Yes, I did a test and it also hangs in guest, before we figure it out,
maybe you try udp with uperf with this case?

VM   -> Host
Host -> VM
VM   -> VM

Here are averaged run numbers (Gbps throughput) across 4.12, 4.13 and
net-next with and without Jason's recent "vhost_net: conditionally
enable tx polling" applied (referred to as 'patch' below).  1 uperf
instance in each case:

uperf TCP:
	 4.12	4.13	4.13+patch	net-next	net-next+patch
----------------------------------------------------------------------
VM->VM	 35.2	16.5	20.84		22.2		24.36
VM->Host 42.15	43.57	44.90		30.83		32.26
Host->VM 53.17	41.51	42.18		37.05		37.30

uperf UDP:
	 4.12	4.13	4.13+patch	net-next	net-next+patch
----------------------------------------------------------------------
VM->VM	 24.93	21.63	25.09		8.86		9.62
VM->Host 40.21	38.21	39.72		8.74		9.35
Host->VM 31.26	30.18	31.25		7.2		9.26

The net is that Jason's recent patch definitely improves things across
the board at 4.13 as well as at net-next -- But the VM<->VM TCP numbers
I am observing are still lower than base 4.12.

A separate concern is why my UDP numbers look so bad on net-next (have
not bisected this yet).