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Date: Tue, 24 Jan 2006 08:30:53 +0800
From: David Xu <davidxu@freebsd.org>
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To: Julian Elischer <julian@elischer.org>
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Cc: freebsd-current@freebsd.org
Subject: Re: kernel thread as real threads..
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Julian Elischer wrote:

>
> John Baldwin wrote:
>
>> On Thursday 19 January 2006 21:56, Julian Elischer wrote:
>>  
>>
>>> some progrsss..
>>> as the first few lines show, it's not quite perfect yet but it's 
>>> most of
>>> the way there..
>>> (Like proc 1 isn't init)
>>>   
>>
>>
>> One other note, watch out for the AIO daemons.  They have to be 
>> kernel procs and not kthreads because they borrow the vmspace of the 
>> user process when performing AIO on another process' behalf.
>>
>>  
>>
> yeah I found that and the patches account for that.
>
> However I would like to suggest that we change the way that aio works..
>
> My suggestion is that when a process does AIO, that we "fork a 
> ksegroup" and attach it to the
> process, and assign it a (or some) worker thread to do the aio work.  
> The userland process would
> be oblivious of the extra (kernel) threads in that kseg and they would 
> be independently schedulable.
> They would however automatically have full access to the correct 
> address space.
>
These threads should be invisible to userland debugger, and other code
current unknown, for example, signal code ? The idea seems simply but we
may in fact encounter problem, because you inject unknown threads to a
process. :-)
I still prefer current model, also the aiod threads can be reused for 
multiple
processes.