Subject: Re: CVS commit: [itohy-usb1] src/sys/dev/usb
To: M. Warner Losh <imp@bsdimp.com>
From: Daniel Carosone <dan@geek.com.au>
List: source-changes
Date: 06/27/2007 14:26:17
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On Tue, Jun 26, 2007 at 09:57:36PM -0600, M. Warner Losh wrote:
> FreeBSD's mutexes protect data, while NetBSD splusb protects code.
> The fine grain locking that's been introduced into recent NetBSD
> versions might help change this, but it took FreeBSD 5 years to lock
> down the kernel to the point where Giant doesn't cover much these
> days.

I suspect the differences, from the perspective of a driver writer,
need not be so great (even if the underlying mutex and scheduler
implementations differ to a greater extent).  Moreover, I suggest
Making It So would be a worthy goal in itself.

Where does DragonFly fit in this spectrum, as yet a different take on
the model?

> If there's a good way around these issues that I've not seen, I'm all
> ears.

Yeah; I guess the point is that the usb code (with the commonality it
already has) is probably the best and most convenient concrete example
with which to explore exactly this question.

--
Dan.

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