Linux has a well-established foundation for implementation of device drivers in the kernel. For high-end performance - interrupt latency and throughput – there has been much recent focus on user space driver implementations. Linux kernel drivers have issues like syscall overhead, interrupt latency, debugging (different tools for kernel debug vs user space debug), language options, etc. User space drivers potentially offer better interrupt latency and throughput, but at some serious cost. Interrupt handling, DMA, device interdependencies (bridged devices), access to kernel services, and multiple client access are but a few of the issues for a user space driver. This presentation will review these issues and report some results from real studies. In summary, there will be a discussion on Intel’s DPDK, Freescale’s USDPAA, TI’s TransportnetLib, and Linaro’s ODP regarding this topic.