[dpdk-users] VHOST-USER interface between ovs-dpdk and a VM

[Avi Cohen (A)]

Sorry - step 4 below is incorrect:
There is a copy between guest OS and guest user-space.
Now the question is - what is the different of # of copies (copies of packet from host to guest application) between this setup (OVS-DPDK) and setup with standard OVS (no dpdk)
Best regards

> -----Original Message-----
> From: Avi Cohen (A)
> Sent: Tuesday, 23 May, 2017 4:27 PM
> To: users at dpdk.org
> Subject: VHOST-USER interface between ovs-dpdk and a VM
> 
> Hi,
> I'm trying to understand the packet life-cycle in   ovs-dpdk  (running on host)
> communicating with  a VM through vhost-user interface:
> 1. packet is received via physical port to the device.
> 2.DMA  transfer   to mempools on huge-pages  allocated by dpdk-ovs - in  user-
> space.
> 3. ovs-dpdk copies this packet to the shared-vring of the associated  guest
> (shared between ovs-dpdk userspace process and guest) 
[Avi Cohen (A)] 
4. no more copies in
> the guest - i.e. when any application running on the guest wants to consume the
> packet - there is a zero copy between the shared-vring and the guest
> application.
> 
> Is that correct ? how 4  is implemented ?  this is a communication between OS
> in guest and application in guest . so how this is implemented with zero copy ?
> 
> Best Regards
> avi