On Thursday 12 June 2003 09:39 pm, John Lapeyre wrote: > I seem to recall setting the dma. I think there may have > been some problem with that in relation to the promise controller. > I'll revisit that. By the way, the hardware works great if I put in a > usb-2.0 mass-storage external case. I wonder why not using dma would > slow the clock down, etc...
DMA is Direct Memory Access... If it is not enabled the CPU uses cycles to transfer data from the device to the memory; with DMA enabled the device transfers data directly to the memory, bypassing the CPU... that is why if you do not have DMA enabled you'll see that the CPU uses more cycles for playback. As for the USB 2 linked device, I am not sure... I know that DMA is disabled on CD/DVD for some reason I do not remember, to avoid some problem in some systems, but is enableable... I do not know if that apply to other devices (firewire/USB2, etc), may be not. By the way, How do you use the USB2 device... what kernel do you have... I though that USB2 support was available only from kernel 2.5 and above!. -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
