[dpdk-dev] [Q] asymmetric ping latency over KNI

[dpdk-dev] [Q] asymmetric ping latency over KNI

[Moon-Sang Lee]

hello.
I installed dpdp-2.1.0 on my ubuntu 14.04 server where two NIC ports are
available.
There are two KNI interfaces, vEth0 and vEth1, for two NIC ports. (i.e. one
KNI for one NIC port)
And I connected two servers, M1 and M3, to each NIC port as below.

[ M1 ]--------eth0-[ M2 ]-eth1--------[ M3 ]
                 (vEth0)       (vEth1)

After running KNI example in dpdk-2.1.0 source tree,
I pinged from M1 to M2(eth0) and from M3 to M2(eth1).

It shows short latency over M1-M2, but large latency (1 second) over M2-M3.
If I put "-i 0.2" option to ping, the large latency reduces to 200ms.
If I put "-i 0.x", then the latency becomes 0.x secnod.

I can't figure out what's wrong with my configuration and running
parameters.
Any comments are appreciated.

my runtime environment as follows.

# loading kni driver
insmod igb_uio.ko
insmod rte_kni,ko lo_mode=lo_mode_ring_skb

# execute kni example (i.e. packet burst size is the default, 32)
a.out -c 0x1414 -n 4 -- -p 0x3 -P --config="(0,2,4,6),(1,10,12,14)"


-- 
Moon-Sang Lee, SW Engineer
Email: sang0627@gmail.com
Wisdom begins in wonder. *Socrates*