On Mon, Nov 22, 2010 at 11:03:15AM +0100, Sébastien Michel wrote: > Since strace doesn't help to see what mmap reads on SELECT, so I made a test > on NFS server. On Linux you should use blktrace. NFS is a non-POSIX filesystem, and it may show quite different behavior compared to a POSIX filesystem on a real block device. Gabor