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    SubjectRe: [PATCH RFC] rcu: Permit limiting of force_quiescent_state() latency
    On Sun, 2012-03-18 at 17:10 -0700, Paul E. McKenney wrote:

    > Thank you very much for your efforts on this!!!

    No problem, irq holdoff troubles are worth effort.

    > Given that you were seeing about 200-microsecond latency spikes on
    > grace-period initialization, I would expect that you would need about
    > 200 dyntick-idle CPUs for force_quiescent_state() to give you a
    > ten-microsecond spike, so I am not surprised that you could not see
    > the difference on 60 CPUs, which probably have given you something
    > like 3 microseconds..

    Crawling over fewer locks should still save cycles, so I'll measure.
    Big box rt needs every little usec we can scrape together.


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