Re: [OFFTOPIC] Re: IDE-DMA strangeness (another one)

Kurt Garloff (
Sat, 5 Dec 1998 09:47:26 +0100

On Fri, Dec 04, 1998 at 12:11:30AM +0000, Mark Lord wrote:
> > Does this mean I'm using (roughly, at least, on
> > average) 11.19/16.66 ~= 2/3 of the CPU's processing
> > power PIO-ing things off the drive (in e.g. a long
> No. It just means that the drive can deliver data
> at at least 11MByte/sec from the platters. Nothing more.

Yes it does mean it.
See other posting in this thread.
Assuming the drive reads 112MB, this takes 112MB/11.2MB/s = 10secs.
This data will be transfered via PIO in several chunks which need altogether
112MB/16.7MB/s = 6.7s. Now, during PIOing data, the CPU can't do anything
else, so CPU consumed is 6.7s/10s ~= 2/3. qed.

Kurt Garloff <>  (Dortmund, FRG)
PGP key on

>There is something frustrating about the quality and speed of Linux >development. I.e. the quality is too high and the speed is too high, in >other words, I can implement this XXXX feature, but I bet someone else >has already done it and is just about to release his patch to Linus soon... [From a posting of Tigran Aivazian to linux-kernel, XXXX = disk stat]

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