Re: [PATCH, RFC] v7 scalable classic RCU implementation

From: Paul E. McKenney
Date: Mon Oct 27 2008 - 12:46:19 EST


On Wed, Oct 22, 2008 at 11:24:30PM +0200, Manfred Spraul wrote:
> Paul E. McKenney wrote:
>> Hmmm... Looks like rcu_pending is also always called with its cpu
>> parameter set to the current CPU, and same for rcu_needs_cpu().
>> And given that all the external uses of rcu_check_callbacks() are
>> of the following form:
>>
>> if (rcu_pending(cpu))
>> rcu_check_callbacks(cpu, whatever);
>>
>>
>> perhaps rcu_pending() should be an internal-to-RCU API invoked from
>> rcu_check_callbacks().
>>
>> Thoughts?
>>
> From my point of view: Yes, change it.
>
> In the long run, I'd like to move the stall detector code to rcupdate.c,
> with an 'rcu_cpu_missing' callback. That one would need a cpu flag, but
> that's a new function.

Agreed. Perhaps a good change to make while introducing stall detection
to preemptable RCU -- there would then be three examples, which should
allow good generalization.

Thanx, Paul
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