linux-kernel - Re: [PATCH 0 of 4] Generic AIO by scheduling stacks

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Message-Id: <1170220576.26655.381.camel@localhost.localdomain>
Date:	Wed, 31 Jan 2007 16:16:16 +1100
From:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Zach Brown <zach.brown@...cle.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	linux-aio@...ck.org, Suparna Bhattacharya <suparna@...ibm.com>,
	Benjamin LaHaise <bcrl@...ck.org>, Ingo Molnar <mingo@...e.hu>
Subject: Re: [PATCH 0 of 4] Generic AIO by scheduling stacks


> 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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