linux-kernel - Re: [GIT PULL] RCU changes for v3.3

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Message-ID: <1327448809.14373.6.camel@edumazet-laptop>
Date:	Wed, 25 Jan 2012 00:46:49 +0100
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	paulmck@...ux.vnet.ibm.com
Cc:	Ingo Molnar <mingo@...e.hu>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	linux-kernel@...r.kernel.org,
	Frédéric Weisbecker <fweisbec@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [GIT PULL] RCU changes for v3.3

Le mardi 24 janvier 2012 à 15:29 -0800, Paul E. McKenney a écrit :

> And here is another version of the patch.
> 
> 							Thanx, Paul
> 
> ------------------------------------------------------------------------
> 
> x86: Avoid invoking RCU when CPU is idle
> 
> The idle loop is a quiscent state for RCU, which means that RCU ignores
> CPUs that have told RCU that they are idle via rcu_idle_enter().  There
> are nevertheless quite a few places where idle CPUs use RCU, most commonly
> indirectly via tracing.  This patch fixes these problems for x86.
> 
> Many of these bugs have been in the kernel for quite some time, but
> Frederic's recent change now gives warnings.
> 
> This patch takes the straightforward approach of pushing the
> rcu_idle_enter()/rcu_idle_exit() pair further down into the core
> of the idle loop.
> 
> Signed-off-by: Paul E. McKenney <paul.mckenney@...aro.org>
> Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
> 

Oh well, just when I decided to sleep a bit, you send a new patch :)

This seems to remove the warnings at least on my x86_64 server, thanks !

Tested-by: Eric Dumazet <eric.dumazet@...il.com>



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