[PATCH v4 for 4.14 1/3] membarrier: Provide register expedited private command
Peter Zijlstra
peterz at infradead.org
Fri Sep 29 21:45:18 AEST 2017
On Fri, Sep 29, 2017 at 09:38:53PM +1000, Nicholas Piggin wrote:
> Not really. There is some ability to hold onto a line for a time, but
> there is no way to starve them, let alone starve hundreds of other
> CPUs. They will request the cacheline exclusive and eventually get it.
OK, hardware fairness there is nice.
> I would really prefer to go this way on powerpc first. We could add the
> the registration APIs as basically no-ops, but which would allow the
> locking approach to be changed if we find it causes issues. I'll try to
> find some time and a big system when I can.
Fair enough I suppose.
> > A semi related issue; I suppose we can do a arch upcall to flush_tlb_mm
> > and reset the mm_cpumask when we change cpuset groups.
>
> For powerpc we have been looking at how mm_cpumask can be improved.
> It has real drawbacks even when you don't consider this new syscall.
What else do you use mm_cpumask for?
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