User space scheduling, 2nd try

Robert Kaiser rob at
Fri Jan 24 14:43:13 CET 2003

Hi Kevin,

Am Freitag, 24. Januar 2003 00:52 schrieb Kevin Elphinstone:
> Checkout Ford et al. "CPU inheritance scheduling", OSDI 96
> and for a look at L4 in particular
> Simon Winwood
> Flexible scheduling mechanisms in L4, BE Thesis, SCS&E, UNSW, November
> 2000.

Thanks a lot for these links. At first glance, the Ford paper seems to 
describe pretty much what I had in mind (but I have to study it further).

> Have a look at Dresden as well for a more real-time slant on scheduling in
> L4. I believe they use multi-level round robin and a variation on priority
> inheritance (helping).

Interesting! Our P4 kernel implements this too :-).

> I can't convey the exact details of priority
> assignment etc, so your better off having a look yourself.

I haven't found any publications along these lines yet. Is anyone from 
Dresden listening ? 

> I believe Jochen envisaged something "better" than proportional share, but
> still keeping the flexibility, decomposability, and preserving performance.
> However, this never got beyond being a vision except for the existence of
> preempters (time slice + total quanta ideas) in V4, which is unfinished
> work.

Well, maybe it's time to push this work a little further ? I would be 


Robert Kaiser                         email: rkaiser at
Am Pfaffenstein 14                    phone: (49) 6136 9948-762
D-55270 Klein-Winternheim / Germany   fax:   (49) 6136 9948-10

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