On Wed, 2002-09-18 at 21:23, David S. Miller wrote:

The x86 processor has a well defined timing for executing inb
etc. instructions, the timing is fixed and is independant of the
speed of the PCI bus the device is on.

Earth calling Dave Miller

The inb timing depends on the PCI bus. If you want proof set a Matrox
G400 into no pci retry mode, run a large X load at it and time some inbs
you should be able to get to about 100 milliseconds for an inb to
execute