The DPDK will put received data into userspace buffers using DMA, so what’s the DMA mapping used by DPDK? Is it coherent map or streaming map?

To my understanding, if use coherent map, then the read performance will be impacted since the cache is disabled. But if using streaming map, the memory coherent problem will occur. Since DPDK works in user space, it seems that no way to flush cache in user space before userspace application accessing the newly DMAed memory.