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

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Date:	Tue, 10 Nov 2009 22:33:12 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	David Rientjes <rientjes@...gle.com>
Cc:	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,
	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


* 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
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