(x86_64/amd64) by default. I experimented for a while with the ahci driver; bigger values helped to increase linear (dd) performance by up to 20% with fast SSDs but it was unclear at the time if it would have improved regular filesystem operations.
it should when performing parallel reads/writes on multiple large files. prevents seeking. in freebsd it makes enormous difference.
Even though all storage drivers compile fine with bigger MAXPHYS values it's also possible some will have issues at runtime. -- Francois Tigeot
