Messages in this thread | | | Date | Thu, 27 Jul 2017 07:33:08 -0700 | From | "Paul E. McKenney" <> | Subject | Re: [PATCH tip/core/rcu 4/5] sys_membarrier: Add expedited option |
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On Thu, Jul 27, 2017 at 03:37:29PM +0200, Peter Zijlstra wrote: > On Thu, Jul 27, 2017 at 05:56:59AM -0700, Paul E. McKenney wrote: > > On Thu, Jul 27, 2017 at 12:14:26PM +0200, Peter Zijlstra wrote: > > > On Tue, Jul 25, 2017 at 12:36:12PM -0700, Paul E. McKenney wrote: > > > > This horse is already out, so trying to shut the gate won't be effective. > > > > > > So I'm not convinced it is. The mprotect() hack isn't portable as we've > > > established and on x86 where it does work, it doesn't (much) perturb > > > tasks not related to our process because we keep a tight mm_cpumask(). > > > > Wrong. People are using it today, portable or not. If we want them > > to stop using it, we need to give them an alternative. Period. > > What's wrong? The mprotect() hack isn't portable, nor does it perturb > other users much. > > I would much rather they use this than your > synchronize_sched_expedited() thing. Its much better behaved. And > they'll run into pain the moment they start using ARM,PPC,S390,etc..
What is wrong is that we currently don't provide them a reasonable alternative.
Thanx, Paul
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