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    SubjectRe: rcu: endless stalls
    On Mon, Jun 11, 2012 at 04:22:23PM +0200, Mike Galbraith wrote:
    > On Mon, 2012-06-11 at 06:39 -0700, Paul E. McKenney wrote:
    > > On Mon, Jun 11, 2012 at 12:06:16PM +0200, Mike Galbraith wrote:
    > > > Greetings,
    > > >
    > > > I received a report of a 48 core UV box hitting a gripe, taking longer
    > > > than timeout to emit same, so box griped endlessly, forcing reboot.
    > >
    > > So it took minutes to print an RCU CPU stall warning? On only 48 CPUs?
    > >
    > > If so, yow!!!
    >
    > The report was a tad fuzzy on details, but serial console can take a
    > while at low baud rate, and the box was apparently perma-stalled.

    Which clearly demands the question "why not increase the serial-console
    baud rate"... ;-)

    Thanx, Paul

    > > My guess is that rcu_cpu_stall_suppress must be manipulated atomically
    > > for this to work reliably, for example, using xchg().
    >
    > Ah, thanks.
    >
    > -Mike
    >



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