linux-kernel - Re: [patch v2] x86: reduce srat verbosity in the kernel log

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Date:	Tue, 10 Nov 2009 13:42:40 -0800
From:	Yinghai Lu <yinghai@...nel.org>
To:	Ingo Molnar <mingo@...e.hu>
CC:	David Rientjes <rientjes@...gle.com>, Mike Travis <travis@....com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jack Steiner <steiner@....com>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
	Mel Gorman <mel@....ul.ie>, linux-kernel@...r.kernel.org,
	linux-acpi@...r.kernel.org, Andi Kleen <andi@...stfloor.org>
Subject: Re: [patch v2] x86: reduce srat verbosity in the kernel log

Ingo Molnar wrote:
> * David Rientjes <rientjes@...gle.com> wrote:
> 
>> On Tue, 27 Oct 2009, David Rientjes wrote:
>>
>>> x86: reduce srat verbosity in the kernel log
>>>
>>> It's possible to reduce the number of SRAT messages emitted to the kernel
>>> log by printing each valid pxm once and then creating bitmaps to represent
>>> the apic ids that map to the same node.
>>>
>>> This reduces lines such as
>>>
>>> 	SRAT: PXM 0 -> APIC 0 -> Node 0
>>> 	SRAT: PXM 0 -> APIC 1 -> Node 0
>>> 	SRAT: PXM 1 -> APIC 2 -> Node 1
>>> 	SRAT: PXM 1 -> APIC 3 -> Node 1
>>>
>>> to
>>>
>>> 	SRAT: PXM 0 -> APIC {0-1} -> Node 0
>>> 	SRAT: PXM 1 -> APIC {2-3} -> Node 1
>>>
>>> The buffer used to store the apic id list is 128 characters in length.
>>> If that is too small to represent all the apic id ranges that are bound
>>> to a single pxm, a trailing "..." is added.  APICID_LIST_LEN should be
>>> manually increased for such configurations.
>>>
>>> Acked-by: Mike Travis <travis@....com>
>>> Signed-off-by: David Rientjes <rientjes@...gle.com>
>> Ingo, have you had a chance to look at merging this yet?
> 
> I'm waiting for Mike to test them (and other patches) and send a new 
> series out with bits to pick up.
> 
> But i really dont like such type of buffering - in the past they tended 
> to be problematic. Why print this info at all in the default bootup?  
> It's not needed on a correctly functioning system.
> 
> For failure analysis make it opt-in available via a boot parameter (if 
> it's needed for bootup analysis) - but otherwise just dont print it.
> 
make them to depend on apic=debug or apic=verbose?

YH
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