API is the same. Memory map if you prefer that access style and it suits your OS/language preferences. The OS will almost certainly not let you map straight across into the device's PCI memory mapped window so you'll incur a copy to userspace penalty either way. Benchmark. There is probably no longer any advantage to a sequential write, but you still have a per-syscall and per-IOP overhead, so large writes will be faster than N small ones. Disk caching is still there and still decreases latency but isn't so critical.