> Lennart Augustsson <lennart@augustsson.net> writes:
> 
> > Yes, DMA can still happen while interrups are off.  On the PCI bus any
> > bus mastering device can do cycles.  E.g., if you have a USB
> > controller it will access memory every ms regardless of any transfers
> > that have been set up.
> 
> Thanks!  So you are saying that if I disable USB support in the kernel
> the controller will still do cycles? 

If support is disabled, then the chip is not initialized so it should
stay quiet. To benchmark memory-to-memory DMA, you probably want to
disable all the devices that behave as bus-masters, to make sure you
(CPU) are the only one accessing the RAM at the moment.

	Regards,
		-- Jachym Holecek