linux-kernel - Re: [PATCH] x86_64: Limit the number of processor bootup messages

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Message-ID: <4AEEBE65.3070202@linux.intel.com>
Date:	Mon, 02 Nov 2009 12:11:33 +0100
From:	Andi Kleen <ak@...ux.intel.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>,
	Greg Kroah-Hartman <gregkh@...e.de>,
	Yinghai Lu <yinghai@...nel.org>,
	"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 <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86_64: Limit the number of processor bootup messages

Mike Travis wrote:
> 
> 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.   Most of the messages are also sent to the kernel log
> buffer as KERN_DEBUG messages so it can be used to examine more closely any
> details specific to a processor.

What would be good is to put the information from the booting CPUs
into some buffer and print it visibly if there's a timeout detected on the BP.

Also power of two summaries at a bit odd, but ok.

> For Processor Information printout:
> 
>     [   90.968381] Summary Processor Information for CPUS: 0-639
>     [   90.972033] Genuine Intel(R) CPU    0000 @ 2.13GHz stepping 04

It would be good to print family/model in this line

>     [   90.981402] CPU: L1 I cache: 32K, L1 D cache: 32K
>     [   90.985888] CPU: L2 cache: 256K
>     [   90.988032] CPU: L3 cache: 24576K

I would recommend to drop the cache information; this can be easily
gotten at runtime and is often implied in the CPU name anyways
(and especially L1 and increasingly L2 too change only very rarely)

>     [   90.992032] MIN 4266.68 BogoMIPS (lpj=8533371)
>     [   91.000033] MAX 4267.89 BogoMIPS (lpj=8535789)

Perhaps an average too? You could put all that on one line.


> These lines have been moved to loglevel KERN_DEBUG:
> 
>     CPU: Physical Processor ID:
>     CPU: Processor Core ID:
>     CPU %d/0x%x -> Node %d
>     <cache line sizes per cpu>

I think you can just remove them.

>     CPUx is down

This should be still printed if there's a timeout, or rather print
a "CPUx is not down" message. Right now there's no timeout detection on shutdown, but
I guess that wouldn't be too hard to add.

-Andi
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