Messages in this thread | | | Subject | Re: Question about DMA and cd burning. | From | Alan Cox <> | Date | 26 Feb 2003 19:38:52 +0000 |
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On Wed, 2003-02-26 at 17:02, Richard B. Johnson wrote: > This has turned out to be a FAQ. DMA is not "better" > than some other transfer mode. It's just a method.
In the IDE world that isnt quite so. The IDE world has other limits depending on PIO versus DMA setup which make your explanation, while correct for the general case incorrect for the IDE world.
DMA is a lot better than other transfer modes on IDE devices, not only because PIO burns CPU but because of the cable timings. IDE normally goes up to PIO4, PIO4 is equivalent to MWDMA2. IDE DMA then goes up to UDMA133/150 with SATA. So PIO limits you to a fair bit under 10Mbytes/second, while UDMA133 generally comes down to your PCI bus capability.
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