Subject: Re: [PATCH 0 of 4] Generic AIO by scheduling stacks
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Zach Brown <zach.brown@oracle.com>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
       linux-aio@kvack.org, Suparna Bhattacharya <suparna@in.ibm.com>,
       Benjamin LaHaise <bcrl@kvack.org>, Ingo Molnar <mingo@elte.hu>
In-Reply-To: <Pine.LNX.4.64.0701301838110.3611@woody.linux-foundation.org>
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	 <Pine.LNX.4.64.0701301838110.3611@woody.linux-foundation.org>
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Date: Wed, 31 Jan 2007 16:16:16 +1100
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> NOTE! This is with the understanding that we *never* do any preemption. 
> The whole point of the microthreading as far as I'm concerned is exactly 
> that it is cooperative. It's not preemptive, and it's emphatically *not* 
> concurrent (ie you'd never have two fibrils running at the same time on 
> separate CPU's).

That makes it indeed much less worrisome...

> If you want preemptive of concurrent CPU usage, you use separate threads. 
> The point of AIO scheduling is very much inherent in its name: it's for 
> filling up CPU's when there's IO.

Ok, I see, that's in fact pretty similar to some task switching hack I
did about 10 years ago on MacOS to have "asynchronous" IO code be
implemented linearily :-)

Makes lots of sense imho.

Ben.


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