Hi Mikyung,
I don't see any obvious problems there, but IIRC there is a lot of config required to make this work... I guess for completeness you could show us how you've configured your host NICs and drivers and same for guests? And relevant flow control settings on your switch/es, host and guests (I believe you might need to be setting qos parameters in the guest if you are not already)? Are you using the same OFED inside the guests/VMs?
Cheers,