Re: [PATCH 0/2 v2] rcu: Fix series of spurious RCU softirqs

From: Frederic Weisbecker
Date: Fri Dec 10 2010 - 16:14:53 EST


(Adding Lai in Cc, I forgot my script doesn't handle Suggested-by: tags :)

On Fri, Dec 10, 2010 at 10:11:09PM +0100, Frederic Weisbecker wrote:
> Hi,
>
> Following Lai's idea.
>
> An example of such series of spurious softirqs:
>
> http://tglx.de/~fweisbec/trace_rcu_softirq.txt
>
> In that example, the rcu softirq is raised at every tick
> during 20 secs (was perhaps more, but the trace snapshot happened
> during 20 secs). It happens randomly.
>
> Ah and it survived several hours of rcutorture (with rcu cpu stall
> detection).
>
> Thanks.
>
> Frederic Weisbecker (2):
> rcu: Stop chasing QS if another CPU did it for us
> rcu: Keep gpnum and completed fields synchronized
>
> kernel/rcutree.c | 17 +++++++++++++++++
> 1 files changed, 17 insertions(+), 0 deletions(-)
>
> --
> 1.7.3.2
>
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