Re: [PATCH, RFC] hacks to allow -rt to run kernbench on POWER

[Paul E. McKenney]

On Tue, Oct 30, 2007 at 07:37:50AM +1100, Benjamin Herrenschmidt wrote:
> 
> On Mon, 2007-10-29 at 13:26 -0700, Paul E. McKenney wrote:
> > 
> > > I see a lot of case where you add preempt_disable/enable around
> > areas
> > > that have the PTE lock held...
> > > 
> > > So in -rt, spin_lock doesn't disable preempt ? I'm a bit worried...
> > > there are some strong requirements that anything within that lock is
> > not
> > > preempted, so zap_pte_ranges() is the obvious ones but all of them
> > would
> > > need to be addressed.
> > 
> > Right in one!  One of the big changes in -rt is that spinlock critical
> > sections (and RCU read-side critical sections, for that matter) are
> > preemptible under CONFIG_PREEMPT_RT.
> > 
> > And I agree that this patchset will have missed quite a few places
> > where
> > additional changes are required.  Hence the word "including" above,
> > rather
> > than something like "specifically".  ;-)
> 
> Ok, well, I'm pretty familiar with that MM code since I wrote a good
> deal of the current version so I'll try to spend some time with your
> patch have a look. It may have to wait for next week though, but feel
> free to ping me if you don't hear back, in case it falls through the
> hole in my brain :-)

Works for me!!!

							Thanx, Paul
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