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

- From: Frederic Weisbecker \<hidden\>
- Date: 2012-08-23 10:58:30 
- List: linux-alpha
- Page: https://ratatoskr.run/linux-alpha/2012/08/3913388
- Thread: https://ratatoskr.run/linux-alpha/2012/08/3912938/t.md

```text
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 <redacted>

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