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Date: Mon, 23 Jul 2012 00:51:43 -0700
From: Julian Elischer <julian@freebsd.org>
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To: Robert Watson <rwatson@freebsd.org>
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Cc: Matthew Jacob <mj@feral.com>, freebsd-arch@freebsd.org
Subject: Re: aio in GENERIC?
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On 7/22/12 9:53 AM, Robert Watson wrote:
>
> On Wed, 18 Jul 2012, Matthew Jacob wrote:
>
>> What practically does aio offer that is not achieved via pthreads 
>> other than slightly simpler code?
>
> Although the VFS side of the AIO code blocks kernel threads during 
> in-progress I/O, the socket side is able to do fully asynchronous 
> I/O down the stack without committing a kernel thread to it.  As 
> such, it probably is actually significantly more scalable, allowing 
> larger numbers of simultaneous outstanding I/Os in the network 
> layer, and more efficiently than simply using threads.

this is the reason that the cisco web security appliance uses aio and 
kevent but is generally not threaded...

>
> Robert
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