locked VPP version 19.04 - Confusing with vlib_buffer and rte_mbuf (use DPDK as interface input) referent count operations #vpp


Hi, everyone

I'am a newer with VPP architeture,  I want't to use the vlib_buffer reference count(such as clone) to reduce the copies, 
but I'am confused with the referent count  operations between the vlib_buffer and rte_mbuf (use DPDK as the interface input),  I have searched the mailing list and know about the DPDK take buffer from VPP,  but I'am still confused with these memory implementations, 

Is there anyone 
 give some key points about the relationship between the rte_mbuf and vlib_buffer memory implementation, such as how DPDK take buffer from VPP and  allocation/free between the two parts?