linux-kernel - Re: [PATCH] nohz: remove "Switched to NOHz mode" debugging messages

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Message-ID: <20110824055216.GA2511@osiris.boeblingen.de.ibm.com>
Date:	Wed, 24 Aug 2011 07:52:16 +0200
From:	Heiko Carstens <heiko.carstens@...ibm.com>
To:	Stephen Boyd <sboyd@...eaurora.org>
Cc:	Joe Perches <joe@...ches.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...e.hu>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] nohz: remove "Switched to NOHz mode" debugging messages

On Tue, Aug 23, 2011 at 12:15:51PM -0700, Stephen Boyd wrote:
> On 08/23/2011 12:12 PM, Joe Perches wrote:
> > On Tue, 2011-08-23 at 13:20 +0200, Heiko Carstens wrote:
> >> From: Heiko Carstens <heiko.carstens@...ibm.com>
> >>
> >> When performing cpu hotplug tests the kernel printk log buffer gets flooded
> >> with pointless "Switched to NOHz mode..." messages. Especially when afterwards
> >> analyzing a dump this might have removed more interesting stuff out of the
> >> buffer.
> >> Assuming that switching to NOHz mode simply works just remove the printk.
> >> diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
> > []
> >> -
> >> -	printk(KERN_INFO "Switched to NOHz mode on CPU #%d\n", smp_processor_id());
> > Though I don't know if these are actually particularly
> > useful messages, perhaps pr_info_ratelimited() might
> > be appropriate instead.
> 
> Or perhaps a printk_once() would be good. Presumably the second switch
> to NOHz mode wouldn't be as dangerous as the first.

Let's just remove them.
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