Fiasco lazy-scheduling question

Udo A. Steinberg us15 at os.inf.tu-dresden.de
Wed Jan 17 13:03:09 CET 2007


On Wed, 17 Jan 2007 12:51:35 +0100 eschierb at sci.kun.nl (EKN) wrote:

EKN> For one, the description says that the sender is not removed from 
EKN> the ready-list when the switch is made to the receiver (even 
EKN> though it is now in waiting status). However, as the sender is 
EKN> the active thread it is not part of the ready-list by definition 
EKN> (at least that is how I interpreted the system), so how could 
EKN> it be removed anyway?

I would suggest reading Section 3.3.1 of
http://os.inf.tu-dresden.de/papers_ps/steinberg-diplom.pdf
which describes and motivates the lazy-queueing invariant.

EKN> Secondly, the switching from sender to receiver is simply an
EKN> execution context switch. If the receiver finishes before 
EKN> the sender's time is up, does the receiver switch the 
EKN> execution context back to that of the sender?

The kernel performs the execution context switch during IPC. If that's what you
meant, then the answer to your question is "yes".

Cheers,

	- Udo

-- 
Dipl.-Inf. Udo Steinberg                     
Technische Universität Dresden               http://os.inf.tu-dresden.de/~us15
Institute for System Architecture            Tel: +49 351 463 38401
D-01062 Dresden                              Fax: +49 351 463 38284
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