Re: [PATCH RFC tip/core/rcu 2/9] rcu: Provide cond_resched_rcu_qs() to force quiescent states in long loops

[Peter Zijlstra]

On Mon, Jul 28, 2014 at 03:56:13PM -0700, Paul E. McKenney wrote:
> From: "Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx>
> 
> RCU-tasks requires the occasional voluntary context switch
> from CPU-bound in-kernel tasks.  In some cases, this requires
> instrumenting cond_resched().  However, there is some reluctance
> to countenance unconditionally instrumenting cond_resched() (see
> http://lwn.net/Articles/603252/),

No, if its a good reason mention it, if not ignore it.

> so this commit creates a separate
> cond_resched_rcu_qs() that may be used in place of cond_resched() in
> locations prone to long-duration in-kernel looping.

Sounds like a pain and a recipe for mistakes. How is joe kernel hacker
supposed to 1) know about this new api, and 2) decide which to use?

Heck, even I wouldn't know, and I just read the damn patch.

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