Re: [RFC][PATCH v2 08/11] context_tracking,rcu: Replace RCU dynticks counter with context_tracking

[Peter Zijlstra]

On Wed, Sep 29, 2021 at 09:13:26PM +0200, Peter Zijlstra wrote:
> On Wed, Sep 29, 2021 at 11:37:01AM -0700, Paul E. McKenney wrote:
> 
> > And what happens to all of this in !CONFIG_CONTEXT_TRACKING kernels?
> > Of course, RCU needs it unconditionally.  (There appear to be at least
> > parts of it that are unconditionally available, but I figured that I
> > should ask.  Especially given the !CONFIG_CONTEXT_TRACKING definition
> > of the __context_tracking_cpu_seq() function.)
> 
> For !CONFIG_CONTEXT_TRACKING it goes *poof*.
> 
> Since the thing was called dynticks, I presumed it was actually dynticks
> only, silly me (also, I didn't see any obvious !context_tracking usage
> of it, i'll go audit it more carefully.

Oh argh, it does idle too... damn. And I don't suppose having 2 counters
is going to be nice :/

I'll go back to thinking about this.