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

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Message-ID: <20091118104855.GA593@aftab>
Date:	Wed, 18 Nov 2009 11:48:55 +0100
From:	Borislav Petkov <borislav.petkov@....com>
To:	Mike Travis <travis@....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

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?

> 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)
 #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?

-- 
Regards/Gruss,
Boris.

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