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Date: Wed, 23 Nov 2005 17:41:20 -0700
From: Scott Long <scottl@samsco.org>
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To: David Xu <davidxu@freebsd.org>
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Cc: current@freebsd.org, Kris Kennaway <kris@obsecurity.org>
Subject: Re: 4BSD process starvation during I/O
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David Xu wrote:
> Kris Kennaway wrote:
> 
>> On Thu, Nov 24, 2005 at 07:52:30AM +0800, David Xu wrote:
>>  
>>
>>> Kris Kennaway wrote:
>>>
>>>   
>>>
>>>> Perhaps this can be tweaked.
>>>>
>>>> Kris
>>>>
>>>> P.S. Please, no responses about how maybe someone could write a new
>>>> scheduler that doesn't have this property.
>>>>
>>>>
>>>>
>>>>
>>>>     
>>>
>>> Can you try it again with FULL_PREEMPTION is turned on ?
>>>   
>>
>>
>> Didn't really make a difference:
>>
>>  
>>
> This might only can be fixed when msleep no longer explicitly fiddles
> thread priority, let scheduler fully control it.
> 

I don't agree.  The more likely problem according Stephan is that
threads returning from userland get their priority elevated so they have
a better chance of running right away.  If you have plans to change how
tsleep and msleep manage priorities, please discuss it on arch@ before
you start making changes.

Scott