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Date:      Wed, 24 Nov 1999 14:28:35 -0800 (PST)
From:      Julian Elischer <julian@whistle.com>
To:        Matthew Dillon <dillon@apollo.backplane.com>
Cc:        "Daniel C. Sobral" <dcs@newsguy.com>, "Daniel M. Eischen" <eischen@vigrid.com>, freebsd-arch@freebsd.org
Subject:   Re: Threads
Message-ID:  <Pine.BSF.4.10.9911241425090.11412-100000@current1.whistle.com>
In-Reply-To: <199911241835.KAA19645@apollo.backplane.com>

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BTW we have coined KSE "Kerne Schedulabel entity" simply top stop
people confusing each other with words like 'task' which means different
things on different OSs. Your 'Task' IS a 'Kernel Schedulable Entity'.

For it to run it neads context and a stack and the kernel needs to be able
to schedule it.


On Wed, 24 Nov 1999,
Matthew Dillon wrote:

> 
> :Julian, Dan, remember that reducing the overhead of task switching
> :(thread switching) is of vital importance. In that light, the least
> :context that has to be save/restored when a KSE blocks, the better.
> :
> :--
> :Daniel C. Sobral			(8-DCS)
> :dcs@newsguy.com
> :dcs@freebsd.org
> 
>     I am getting confused by this whole KSE thing.  All the threading I've
>     ever implemented has been done simply by splitting out the context
>     information from the Process into a Task, and then allowing N Tasks to
>     reference the same Process.  There was no real distinction made between 
>     kernel and user mode tasks or processes.
> 
>     In such a scheme the switch code need only contain a single conditional:
>     One to check if the governing process for a task has a user-level mmu
>     directory that must be setup.  That's it, done.  
> 
>     I don't think separate scheduling queues are required either.  I can see
>     absolutely no gain in performance by doing that and it unnecessarily
>     complicates the code.  We can trivially use the existing priority 
>     scheme to schedule interrupt tasks (threads).
> 
> 					-Matt
> 					Matthew Dillon 
> 					<dillon@backplane.com>
> 





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