Re: [PATCH 01/10] alpha: Add missing RCU idle APIs on idle loop

From: Frederic Weisbecker
Date: Thu Aug 23 2012 - 06:58:24 EST


On Thu, Aug 23, 2012 at 09:32:18PM +1200, Michael Cree wrote:
> On 23/08/12 04:23, Frederic Weisbecker wrote:
> > In the old times, the whole idle task was considered
> > as an RCU quiescent state. But as RCU became more and
> > more successful overtime, some RCU read side critical
> > section have been added even in the code of some
> > architectures idle tasks, for tracing for example.
>
> Fantastic! It fixes RCU CPU stalls that we were seeing on the SMP
> kernel when built for generic Alpha.
>
> A build of glibc and running its test suite reliably triggers RCU CPU
> stalls when running a kernel built for generic Alpha. I have just built
> glibc and ran its test suite twice with no RCU CPU stalls with this
> patch against a 3.5.2 kernel! Nice. Very nice.
>
> I see the stable queue is CCed but I note the patch does not apply
> cleanly to the 3.2.y kernel. It would be nice to have a backport of the
> patches for the 3.2 stable kernel.

Sure.

>
> So feel free to add:
>
> Tested-by: Michael Cree <mcree@xxxxxxxxxxxx>

Thanks, but I need to refactor the patch, I suspect a problem with CONFIG_PREEMPT.
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