Re: [RFC PATCH] rcu: don't ignore preempt_disable() in the idle loop

From: Lai Jiangshan
Date: Tue Mar 09 2010 - 21:14:16 EST


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
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