Hi, We've recently conducted some tests showing that CPU overhead is significant when sending/receiving data via TCP or UDP over 10GigE cards on Linux (20-50% of an Ivy Bridge core clocked at 3Ghz). A lot of time is spent copying data from kernel to user space and vice versa. As we would like to avoid this overhead as far as possible, does mpich2 support zero copy data transfer using packet mmap? Thank you in advance, Clemens