Subject: Re: FUSYN and RT
From: Steven Rostedt <rostedt@goodmis.org>
To: john cooper <john.cooper@timesys.com>
Cc: Sven Dietrich <sdietrich@mvista.com>,
       "'Inaky Perez-Gonzalez'" <inaky@linux.intel.com>,
       robustmutexes@lists.osdl.org, mingo@elte.hu,
       linux-kernel@vger.kernel.org, "'Esben Nielsen'" <simlo@phys.au.dk>
In-Reply-To: <42610DAC.5070506@timesys.com>
References: <000801c54230$73a0f940$c800a8c0@mvista.com>
	 <42610DAC.5070506@timesys.com>
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Organization: Kihon Technologies
Date: Sat, 16 Apr 2005 10:23:05 -0400
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On Sat, 2005-04-16 at 09:05 -0400, john cooper wrote:
> Sven Dietrich wrote:
[...]
> > This one probably should be a raw_spinlock. 
> > This lock is only held to protect access to the queues.
> > Since the queues are already priority ordered, there is
> > little benefit to ordering -the order of insertion-
> > in case of contention on a queue, compared with the complexity.
> 
> The choice of lock type should derive from both the calling
> context and the length of time the lock is expected to be held.
> 

In this case, I don't think time matters for choice of lock. Time
matters to keep it short since it does need the raw_spin_lock.  This
lock is part of the whole locking scheme, and would be similar to not
using raw_spin_locks in the implementation of rt_mutex.  Well, not
exactly the same, but if we want the fusyn code to use the same code as
rt_mutex for PI, then it will need to be a raw_spin_lock.

-- Steve


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