ahci sata data overruns

[Alan Cox]

> saturates the single lane at 480 MByte/sec.  I'm assuming (perhaps
> incorrectly) that the controller is choking when it receives more data
> from the SATA than it can transmit on the PCIE.

The link has hardware flow control, whether the end result of saturating
the link is poorer performance than not doing so I don't know. That's all
below the level the OS sees.

Alan