"Drivers have been made to behave when using a bigger than 128KB maximum IO transfer size"

[Wojciech Puchar]

> (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
>
>