Re: preemptible RCU bug (was Re: [git pull] scheduler changes for v2.6.25)

From: Paul E. McKenney
Date: Sun Jan 27 2008 - 18:49:42 EST


On Sun, Jan 27, 2008 at 01:26:02PM +0100, Ingo Molnar wrote:
>
> * Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> wrote:
>
> > > Sorry, no help available for this option yet.
> >
> > Good catch!!!
> >
> > This patch supplies help text for the "RCU implementation type" kernel
> > configuration choice.
>
> thanks applied to sched.git. (see the patch below - the config option is
> in init/Kconfig in mainline, not in kernel/Kconfig.preempt)

Ah missed that -- thank you for retargeting the patch.

Thanx, Paul

> Ingo
>
> ------------->
> Subject: RCU: add help text for "RCU implementation type"
> From: "Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx>
>
> This patch supplies help text for the "RCU implementation type"
> kernel configuration choice.
>
> Reported-by: Stefan Richter <stefanr@xxxxxxxxxxxxxxxxx>
> Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
> Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
> ---
>
> init/Kconfig | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> Index: linux/init/Kconfig
> ===================================================================
> --- linux.orig/init/Kconfig
> +++ linux/init/Kconfig
> @@ -779,6 +779,14 @@ config PREEMPT_NOTIFIERS
> choice
> prompt "RCU implementation type:"
> default CLASSIC_RCU
> + help
> + This allows you to choose either the classic RCU implementation
> + that is designed for best read-side performance on non-realtime
> + systems, or the preemptible RCU implementation for best latency
> + on realtime systems. Note that some kernel preemption modes
> + will restrict your choice.
> +
> + Select the default if you are unsure.
>
> config CLASSIC_RCU
> bool "Classic RCU"
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