On Fri, Dec 6, 2019 at 9:32 PM Damjan Marion <dmar...@me.com> wrote: > > > > > On 6 Dec 2019, at 07:16, Prashant Upadhyaya <praupadhy...@gmail.com> wrote: > > > > Hi, > > > > I use VPP with DPDK driver for I/O with NIC. > > For high speed switching of packets to and from kernel, I use DPDK KNI > > (kernel module and user space API's provided by DPDK) > > This works well because the vlib buffer is backed by the DPDK mbuf > > (KNI uses DPDK mbuf's) > > > > Now, if I choose to use a native driver of VPP for I/O with NIC, is > > there a native equivalent in VPP to replace KNI as well ? The native > > equivalent should not lose out on performance as compared to KNI so I > > believe the tap interface can be ruled out here. > > > > If I keep using DPDK KNI and VPP native non-dpdk driver, then I fear I > > would have to do a data copy between the vlib buffer and an mbuf in > > addition to doing all the DPDK pool maintenance etc. The copies would > > be destructive for performance surely. > > > > So I believe, the question is -- in presence of native drivers in VPP, > > what is the high speed equivalent of DPDK KNI. > > You can use dpdk and native drivers on the same time. > How KNI performance compares to tap with vhost-net backend? > > > -- > Damjan >
Thanks Damjan. If I use the native driver for NIC, would I get the vlib buffer still backed by a DPDK mbuf ? I don't know the perf difference between KNI and tap with vhost-net backend. I would need to poll the tap to pick the packets from kernel side; and write into the tap to send the packets to the kernel in VPP workers. I suppose the mere copies from user space into kernel space and vice versa would make it more expensive than KNI where just an exchange of mbuf's takes place in both directions. Plus, I wonder whether system call usage is a good idea at all in a worker which is also multiplexing the packet I/O with the NIC. Regards -Prashant
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