From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Stefan Richter <stefanr@s5r6.in-berlin.de>
Cc: Ingo Molnar <mingo@elte.hu>, linux-kernel@vger.kernel.org
Subject: Re: preemptible RCU bug (was Re: [git pull] scheduler changes for v2.6.25)
Date: Sun, 27 Jan 2008 03:05:59 -0800 [thread overview]
Message-ID: <20080127110559.GB28315@linux.vnet.ibm.com> (raw)
In-Reply-To: <479B87B9.8080005@s5r6.in-berlin.de>
On Sat, Jan 26, 2008 at 08:19:21PM +0100, Stefan Richter wrote:
> Ingo Molnar wrote:
> > - Paul E. McKenney's preemptible RCU code.
>
> BUG: New Kconfig option without help text.
>
> $ make oldconfig
> RCU implementation type:
> > 1. Classic RCU (CLASSIC_RCU) (NEW)
> 2. Preemptible RCU (PREEMPT_RCU) (NEW)
> choice[1-2]: ?
>
> Sorry, no help available for this option yet.
Good catch!!!
This patch supplies help text for the "RCU implementation type"
kernel configuration choice.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
Kconfig.preempt | 8 ++++++++
1 file changed, 8 insertions(+)
diff -urpNa -X dontdiff linux-2.6.24-rt1/kernel/Kconfig.preempt linux-2.6.24-rt1-RCUconfighelp/kernel/Kconfig.preempt
--- linux-2.6.24-rt1/kernel/Kconfig.preempt 2008-01-27 02:52:36.000000000 -0800
+++ linux-2.6.24-rt1-RCUconfighelp/kernel/Kconfig.preempt 2008-01-27 03:05:22.000000000 -0800
@@ -131,6 +131,14 @@ choice
prompt "RCU implementation type:"
default PREEMPT_RCU if PREEMPT_RT
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"
next prev parent reply other threads:[~2008-01-27 11:06 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-01-25 20:37 [git pull] scheduler changes for v2.6.25 Ingo Molnar
2008-01-26 19:19 ` preemptible RCU bug (was Re: [git pull] scheduler changes for v2.6.25) Stefan Richter
2008-01-27 11:05 ` Paul E. McKenney [this message]
2008-01-27 11:16 ` Stefan Richter
2008-01-27 12:26 ` Ingo Molnar
2008-01-27 23:48 ` Paul E. McKenney
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