Re: IBM HDAPS Someone interested?

From: Vojtech Pavlik
Date: Tue Jun 21 2005 - 11:55:19 EST

On Tue, Jun 21, 2005 at 11:37:38AM -0400, Lee Revell wrote:

> On Mon, 2005-06-20 at 17:30 -0400, Adam Goode wrote:
> > Freefall detection: 300 ms
> > Head park time: 300-500 ms
> > (from page 2 of document)
> >
> > Still doesn't seem too bad to figure out how to code though, at least
> > once we can figure out how to get the data stream!
> >
> > P.S. The main control system runs as a Windows kernel driver. Not as
> > safe as full hardware, but probably better than userspace. :)
> >
> Ugh, if userspace can't meet a 300ms RT constraint, that's a pretty
> shitty OS you have there.

It's not that you do one measurement in the 300ms. You need to do at least
100, and some computations, too.

> This should certainly be done in userspace on Linux.

So it's a 3ms RT constraint, which is not as easy.

Vojtech Pavlik
SuSE Labs, SuSE CR
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