Re: [RFC PATCH 4/6] Preempt-RCU: Implementation

From: Roman Zippel
Date: Thu Feb 28 2008 - 23:35:33 EST


Hi,

On Thursday 13. December 2007, Gautham R Shenoy wrote:

> diff --git a/kernel/Kconfig.preempt b/kernel/Kconfig.preempt
> index c64ce9c..06cafcc 100644
> --- a/kernel/Kconfig.preempt
> +++ b/kernel/Kconfig.preempt
> @@ -63,3 +63,41 @@ config PREEMPT_BKL
> Say Y here if you are building a kernel for a desktop system.
> Say N if you are unsure.
>
> +choice
> + prompt "RCU implementation type:"
> + default CLASSIC_RCU
> +
> +config CLASSIC_RCU
> + bool "Classic RCU"
> + help
> + This option selects the classic RCU implementation that is
> + designed for best read-side performance on non-realtime
> + systems.
> +
> + Say Y if you are unsure.
> +
> +config PREEMPT_RCU
> + bool "Preemptible RCU"
> + depends on PREEMPT
> + help
> + This option reduces the latency of the kernel by making certain
> + RCU sections preemptible. Normally RCU code is non-preemptible, if
> + this option is selected then read-only RCU sections become
> + preemptible. This helps latency, but may expose bugs due to
> + now-naive assumptions about each RCU read-side critical section
> + remaining on a given CPU through its execution.
> +
> + Say N if you are unsure.
> +
> +endchoice

Why got this moved into init/Kconfig?
Now it's somewhere in the root menu, not really belonging to anything.
Also why is this a choice? Are more RCU types planned?

bye, Roman
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