Re: System time runs very slow on RiscPC
Am Donnerstag, 21. April 2005 21:31 schrieb David Joy:
> On Thu, 21 Apr 2005, Peter Teichmann wrote:
> > Am Donnerstag, 21. April 2005 01:46 schrieb David Joy:
> >> On an entirely unrelated note, do you know if it is possible to get DMA
> >> working on a RiscPC?
> >
> > In which context?
> >
> > Peter Teichmann
>
> Sorry - on the hard disk (a modern UDMA disk on the built-in RiscPC IDE
> controller).
>
> riscpc:~# hdparm -d1 /dev/hda
>
> /dev/hda:
> setting using_dma to 1 (on)
> HDIO_SET_DMA failed: Operation not permitted
> using_dma = 0 (off)
Oh, I didn't know that you don't know that. That can not work. The hardware of
the RiscPC only supports a (strange variant of a) PIO mode. This limits data
rates to around 2MB/s, and takes 100% cpu time during that. I think there is
support for DMA on other IDE interfaces, but as I do not have one I never
tried.
Peter Teichmann
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