Messages in this thread | | | Date | Tue, 10 Jan 2006 01:27:18 +0000 | From | John Rigg <> | Subject | Re: [Alsa-devel] Re: [OT] ALSA userspace API complexity |
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On Mon, Jan 09, 2006 at 04:29:45PM -0800, David Lang wrote: > On Tue, 10 Jan 2006, John Rigg wrote: > > >>does the CPU touch the data for these, or do you DMA directly from > >>userspace (i.e. "zero-copy")? > > > >The cards I mentioned use DMA. RME actually advertises that some of their > >cards can handle 52 channels with zero CPU load. Their onboard DSPs can > >also do routing and mixing, again without touching the CPU. > > I was under the (apparently mistaken) impression that you couldn't DMA > from userspace (something to do with the possibility that the userspace > memory pages could be swapped out in the middle of the DMA)
Hmm. Maybe I've been paying too much attention to card vendors' sales talk :)
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