Soren Schmidt writes:
>Depends.. There are many factors involved here, using DMA only lowers
>the CPU usage, and will enable faster transfers if the problem was
>that the CPU was saturated with the PIO transfer. It gave about
>double the transfer rate on my old P6 based maschine, because the
>CPU drain was the limitting factor. Most modern CDROM are variable
>speed, and you will see varying rates depending on the quality of
>the media.
dd'ing the whole cd and watching with iostat shows speeds from 2M
increasing to 5.5M on the outside tracks with cpu staying at
98% to 100% idle on a PII 400. So DMA seems to be doing its stuff.
I did try checking for correct data coming off the cd as well, and saw
no problems.
--
Kevin Street
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