Re: DMA Vs Programmed IO

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> > > >
> > > > But quite often if DMA fails for some reson it will
> > > > try to fall back to PIO something working slowly
> > > > can be better than not working at all.
> > >  Is it always useful (even for the small data transfer) to use DMA ?
> >
> > for small transfere it can have the same over head to set up
> > the dma transfere as it does to transfere the data in a case
> > like this there it no point in using DMA
>
> But remember disks are always accessed in terms of blocks and they are
> 512 bytes. Thus the question stands, is DMA setup faster than sending
> 512 bytes to the bus?

who said anything about a disk ?
what about sending a small packet to a nic ?
or some other information somewhere else


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