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

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Message-ID: <20070210104712.GA20878@outpost.ds9a.nl>
Date:	Sat, 10 Feb 2007 11:47:12 +0100
From:	bert hubert <bert.hubert@...herlabs.nl>
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

On Fri, Feb 09, 2007 at 02:33:01PM -0800, Linus Torvalds wrote:

>  - IF the system call blocks, we call the architecture-specific 
>    "schedule_async()" function before we even get any scheduler locks, and 
>    it can just do a fork() at that time, and let the *child* return to the 
>    original user space. The process that already started doing the system 
>    call will just continue to do the system call.

Ah - cool. The average time we have to wait is probably far greater than the
fork overhead, microseconds versus milliseconds. 

However, and there probably is a good reason for this, why isn't it possible
to do it the other way around, and have the *child* do the work and the
original return to userspace?

Would confuse me at lot less in any case.

	Bert

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