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

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Date:	Tue, 10 Nov 2009 15:09:15 -0800
From:	Mike Travis <travis@....com>
To:	Ingo Molnar <mingo@...e.hu>
CC:	David Rientjes <rientjes@...gle.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,
	Yinghai Lu <yinghai@...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.
> 
> 	Ingo

Hi,

Sorry, it's been time consuming getting this checked out as our test
systems are much more in demand right now (SC09 is here.)

I'm very close to submitting another version, just picking up
everyone's comments now.  One more test run this afternoon and
I should be able to submit the patches.  I believe I've got a
good compromise between informative messages and compactness,
without any additional overhead.

I've also tested David's patch in every run and it hasn't shown any
problems at all.  (In fact, a recent merge of ACPI 4.0 code and it
still works flawlessly.)

Thanks,
Mike
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