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Date:      Sun, 31 Oct 1999 17:49:34 -0800 (PST)
From:      Julian Elischer <julian@whistle.com>
To:        Nate Williams <nate@mt.sri.com>
Cc:        freebsd-arch@freebsd.org
Subject:   Re: Threads models and FreeBSD.
Message-ID:  <Pine.BSF.4.05.9910311743490.8816-100000@home.elischer.org>
In-Reply-To: <199911010116.SAA13482@mt.sri.com>

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On Sun, 31 Oct 1999, Nate Williams wrote:

> > > > 3/ Inability of one thread to block aother thread unless they are
> > > > intentionally synchronising.
> > > 
> > > I think this can be dropped, since it's both confusing and almost
> > > contradictory.  There is no such way to 'block' a regular process,
> > > although one can stop it in Unix, so the issue of blocking implies a
> > > blocking on something, which is allowed.
> > 
> > What this means is that if one thread does a read() and blocks, the other
> > threads don't all block.
> > 
> > maybe I should reword it to:
> > "Inability of one thread to unwittingly block another thread during normal
> > operations" ?
> 
> How about the abilty for multiple threads to execute at the same time?
> :)
well that requires multiple processors..

 see #2
maybe I need to make it more explicit?


> 
> The double negative implies that we would not add functionality that
> might be desired.
> 
> > > > 4/ All threads see the same address space (exactly).
> > > > 
> > > > 5/ All threads share the same file resources.
> > > 
> > > All threads share all the same resources (except for thread-specific stack).
> > Well they can see all the other stacks, they just don't use them as the
> > stack. How would you better word that?
> 
> The resources are *all* shared (not just file resources), but each
> thread has it's own thread-specific stack.

ok gimme a better wording.. yours leads me to wonder if there is
somethign special about the mamory a particular thread's stack is on..
(they don't share processor registers BTW, nor do they neccesarily share
proccessors if they have affinity)



> 
> > Richard seaman's work is available. it can be used prety much without 
> > change.. Do we want to do that? 
> 
> Another thing I'd like to add to the requirements list is that the
> threads use 'standard' threading mechanisms for safety, such as
> mutex/semaphore, etc.., which should exist in the kernel as well.
> 
> This is inline with the Posix stuff, and rather than invent our 'own'
> new kind of data structure, I'd like to stick with known solutions that
> work and everyone for the most part understands.
> 
> Howeer, that requirement may be more detailed oriented than what you are
> looking for now.

yes, though maybe a meta-goal of 
'be able to support all pthreads functtionality' is a good idea.
> 
> 
> 
> Nate
> 





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