Message-ID: <42963E61.4080609@timesys.com>
Date: Thu, 26 May 2005 17:23:45 -0400
From: john cooper <john.cooper@timesys.com>
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To: Sven-Thorsten Dietrich <sdietrich@mvista.com>
CC: Andi Kleen <ak@muc.de>, Ingo Molnar <mingo@elte.hu>, dwalker@mvista.com,
       bhuey@lnxw.com, nickpiggin@yahoo.com.au, hch@infradead.org,
       akpm@osdl.org, linux-kernel@vger.kernel.org, john.cooper@timesys.com
Subject: Re: RT patch acceptance
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Sven-Thorsten Dietrich wrote:
> On Thu, 2005-05-26 at 16:38 -0400, john cooper wrote:
>>Spin if the lock is contended and the owner is active
>>on a cpu under the assumption the lock owner's average
>>hold time is less than that of a context switch.  There
>>are restrictions as once a path holds an adaptive
>>mutex as a spin lock it cannot acquire another adaptive
>>mutex as a blocking lock.
> 
> It might be simpler to get things working with a basic implementation
> first, (status quo), and then look into adding something like this. 

I wasn't suggesting this is the time to consider doing so,
but rather pointing it out as an available optimization.

> I don't see how this approach decreases the complexity of the task at
> hand, especially not in regards to concurrency.

It increases the efficiency of the mutex as we don't incur
context switches (in general) unless necessary.  Concurrency
isn't fundamentally affected.

-john


-- 
john.cooper@timesys.com
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