2009/11/3 Micha Nelissen <mi...@neli.hopto.org>: > hank peng wrote: >> >> I remember normal memory copy can also be done (chosen by user) by DMA >> engine on IOP80331(Intel embedded cpu, xscale arch), so why ppc >> platform didn't make use of DMA doing memory copy, I think it can >> increase performance, please correct me if I am wrong! > > AFAIK the DMA engine has only an asynchronous mode (not very smart IMHO). > This means you always have the overhead of context switch + interrupt + > context switch, so the transfer has to be quite large for this to pay off. > but if the amount of data I want to copy is big enough? can we benefit from using DMA in such case? > Micha >
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