linux-kernel - Re: [PATCH 1/5] x86: Limit the number of processor bootup messages

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Message-ID: <4B042C51.7000500@sgi.com>
Date:	Wed, 18 Nov 2009 09:18:09 -0800
From:	Mike Travis <travis@....com>
To:	Borislav Petkov <borislav.petkov@....com>
CC:	Ingo Molnar <mingo@...e.hu>, Thomas Gleixner <tglx@...utronix.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Heiko Carstens <heiko.carstens@...ibm.com>,
	Roland Dreier <rdreier@...co.com>,
	Randy Dunlap <rdunlap@...otime.net>, Tejun Heo <tj@...nel.org>,
	Andi Kleen <andi@...stfloor.org>,
	Greg Kroah-Hartman <gregkh@...e.de>,
	Yinghai Lu <yhlu.kernel@...il.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	David Rientjes <rientjes@...gle.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Rusty Russell <rusty@...tcorp.com.au>,
	Hidetoshi Seto <seto.hidetoshi@...fujitsu.com>,
	Jack Steiner <steiner@....com>,
	Frederic Weisbecker <fweisbec@...il.com>, x86@...nel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/5] x86: Limit the number of processor bootup messages



Borislav Petkov wrote:
> Hi,
> 
> On Tue, Nov 17, 2009 at 01:17:53PM -0600, Mike Travis wrote:
>> When there are a large number of processors in a system, there
>> is an excessive amount of messages sent to the system console.
>> It's estimated that with 4096 processors in a system, and the
>> console baudrate set to 56K, the startup messages will take
>> about 84 minutes to clear the serial port.
>>
>> This set of patches limits the number of repetitious messages
>> which contain no additional information.  Much of this information
>> is obtainable from the /proc and /sysfs.   Some of the messages
>> are also sent to the kernel log buffer as KERN_DEBUG messages so
>> dmesg can be used to examine more closely any details specific to
>> a problem.
>>
>> The list of message transformations....
>>
>> For system_state == SYSTEM_BOOTING:
>>
>> Booting Node   0, Processors  #1 #2 #3 #4 #5 #6 #7 Ok.
> 
> Aren't we missing core 0 here?

Core 0 already booted as it's the Boot CPU.  The info is earlier
in the log.

> 
>> Booting Node   1, Processors  #8 #9 #10 #11 #12 #13 #14 #15 Ok.
>> ..
>> Booting Node   3, Processors  #56 #57 #58 #59 #60 #61 #62 #63 Ok.
>> Brought up 64 CPUs
> 
> Also, I'm getting
> 
> Booting Node   0, Processors  #1
> CPU: L1 I Cache: 64K (64 bytes/line), D cache 64K (64 bytes/line)
> CPU: L2 Cache: 512K (64 bytes/line)

There are other patches that deal with these:

http://git.kernel.org/tip/15cd8812ab2ce62a2f779e93a8398bdad752291a
http://git.kernel.org/tip/b01c845f0f2e3f9e54e6a78d5d56895f5b95e818

>  #2
> CPU: L1 I Cache: 64K (64 bytes/line), D cache 64K (64 bytes/line)
> CPU: L2 Cache: 512K (64 bytes/line)
>  #3
> CPU: L1 I Cache: 64K (64 bytes/line), D cache 64K (64 bytes/line)
> CPU: L2 Cache: 512K (64 bytes/line)
>  #4
> CPU: L1 I Cache: 64K (64 bytes/line), D cache 64K (64 bytes/line)
> CPU: L2 Cache: 512K (64 bytes/line)
>  #5
> CPU: L1 I Cache: 64K (64 bytes/line), D cache 64K (64 bytes/line)
> CPU: L2 Cache: 512K (64 bytes/line)
>  Ok.
> Booting Node   1, Processors  #6
> CPU: L1 I Cache: 64K (64 bytes/line), D cache 64K (64 bytes/line)
> CPU: L2 Cache: 512K (64 bytes/line)
>  #7
> 
> ...
> 
> and clearly CPU cache info is too verbose. We might want to
> kill it since we have it replicated in /sysfs. In that case,
> arch/x86/kernel/cpu/common.c:display_cacheinfo() could become obsolete
> and we could remove it... Or is there some reason for dumping that
> particular information during boot?
> 

Yes, the above patches remove them entirely.

Thanks,
Mike
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