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From: Lai Jiangshan <laijs@cn.fujitsu.com>
To: paulmck@linux.vnet.ibm.com
Cc: Ingo Molnar <mingo@elte.hu>,
	Peter Zijlstra <peterz@infradead.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>,
	josh@joshtriplett.org, LKML <linux-kernel@vger.kernel.org>,
	Frederic Weisbecker <fweisbec@gmail.com>
Subject: Re: [RFC PATCH] rcu: don't ignore preempt_disable() in the idle	loop
Date: Wed, 10 Mar 2010 10:13:56 +0800	[thread overview]
Message-ID: <4B970064.2040802@cn.fujitsu.com> (raw)
In-Reply-To: <20100310013035.GB6203@linux.vnet.ibm.com>

Paul E. McKenney wrote:
>>
>> This is another try, it uses the fact that idle loops
>> are executing with preept_count()=1.
>> But I didn't look deep into all idle loops.
> 
> Hello, Lai!
> 
> One question below...
> 
> 						Thanx, Paul
> 

[...]

>> +
>> +	if ((preempt_count() & PREEMPT_MASK) > IDLE_CORE_LOOP_PREEMPT_COUNT)
>> +		return 0;
> 
> How does this work in CONFIG_PREEMPT=n kernels?  I don't see how it
> does, regardless of what preempt_count() returns in this case.
> 
>

You are right, It cannot work in CONFIG_PREEMPT=n kernels.
ignore this stupid patch.

Thanx, Lai

  reply	other threads:[~2010-03-10  2:14 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-03-09 11:13 [RFC PATCH] rcu: don't ignore preempt_disable() in the idle loop Lai Jiangshan
2010-03-09 12:52 ` Steven Rostedt
2010-03-10  0:57   ` Lai Jiangshan
2010-03-10 13:51     ` Steven Rostedt
2010-03-10  0:54 ` Frederic Weisbecker
2010-03-10  1:30 ` Paul E. McKenney
2010-03-10  2:13   ` Lai Jiangshan [this message]
2010-03-10  2:28     ` Paul E. McKenney

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