Re: IBM HDAPS Someone interested?

From: Valdis . Kletnieks
Date: Tue Jun 21 2005 - 13:19:05 EST

On Tue, 21 Jun 2005 11:37:38 EDT, Lee Revell said:
> On Mon, 2005-06-20 at 17:30 -0400, Adam Goode wrote:
> > Freefall detection: 300 ms
> > Head park time: 300-500 ms

> Ugh, if userspace can't meet a 300ms RT constraint, that's a pretty
> shitty OS you have there.

Actually, it's a lot tighter than that. You need to *issue* the "park head"
command 300-500ms before it hits the ground, and you have 300ms of free fall.

So you may have needed to detect the free fall and issue the command 200ms
before the free fall commences.

That's a *real* hard RT constraint to keep. ;)

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