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SubjectRe: [PATCH, RFC] v6 scalable classic RCU implementation
On Thu, Sep 25, 2008 at 09:29:15AM +0200, Ingo Molnar wrote:
>
> * Paul E. McKenney <paulmck@linux.vnet.ibm.com> wrote:
>
> > Attached is an updated patch to Classic RCU that applies a hierarchy,
> > greatly reducing the contention on the top-level lock for large
> > machines. This passes 10-hour concurrent rcutorture and
> > online-offline testing on 128-CPU ppc64 without dynticks enabled, and
> > exposes some timekeeping bugs in presence of dynticks (exciting
> > working on a system where "sleep 1" hangs until interrupted...).
>
> i'm wondering about those timekeeping bugs. Do you have an idea what's
> it about and does it affect mainline?

Sad to say, they do affect mainline -- I can reproduce these problems
in 2.6.27-rc7. Thomas has given me a couple of fixes that got rid of
earlier problems in which jiffies would stop counting, and I believe
has located the cause of at least one other problem.

Thanx, Paul


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