[cap-talk] Cap type safe OS questions
sam at samason.me.uk
Sun Aug 2 14:25:29 EDT 2009
On Sun, Aug 02, 2009 at 07:21:34PM +0100, Sam Mason wrote:
> On Mon, Aug 03, 2009 at 01:38:03AM +0800, Ben Kloosterman wrote:
> > I think this is mainly due to the high Context switch costs of the common
> > separate user address space , multiple privilege levels OS. The Singularity
> > paper " Singularity - Rethinking the Software Stack " shows good performance
> > with an Asych IPC with an unoptomized kernel compared to L4.
> I was under the impression so far that you had two address spaces, one
> for the kernel and one for everything else. The way you've been talking
> about the kernel fiddling with message queues would suggest that you
> have five address space switches per invocation:
> user -> kernel -> user -> kernel -> user
Sorry, that would be *four*. Not sure what I was thinking there!
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