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DragonFly kernel List (threaded) for 2005-11
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Question about userland scheduler

From: Sergey Glushchenko <deen@xxxxxxxxxx>
Date: Sat, 26 Nov 2005 01:07:18 +0200


Matt, could you please explain yet another time how usched interacts with
LWKT scheduler. I've read your posts in kernel@ from Sat, 15 Nov 2003 and 
Tue, 7 Dec 2004 and still don't get it :(

>   The userland scheduler is responsible ONLY for scheduling threads that
>   are running in userland. The userland scheduler schedules only one such
>   thread at a time, and always at e.g. TDPRI_USER_NORM.  It does not 
>   schedule multiple threads (running in userland) with LWKT at the same 
>   time. 

What means 'only one such thread at a time' and how about other userland

In the situation when we have to schedule TDPRI_USER_NORM thread
(useland thread) it will be choosen by LWKT scheduler according to round-
robin discipline. So, why we need the userland scheduler in this situation?

I know that I'm wrong, so please show me the situation where the
userland scheduler is used and explain how it is used on top of LWKT

And the final question for now: what is gd->gd_uschedcp? Is this a pointer
to the current running process?


Sergey Glushchenko

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