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

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Message-ID: <4E53FC67.7090108@codeaurora.org>
Date:	Tue, 23 Aug 2011 12:15:51 -0700
From:	Stephen Boyd <sboyd@...eaurora.org>
To:	Joe Perches <joe@...ches.com>
CC:	Heiko Carstens <heiko.carstens@...ibm.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 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.

-- 
Sent by an employee of the Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.

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