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

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Date:	Tue, 27 Oct 2009 21:08:46 -0700 (PDT)
From:	David Rientjes <rientjes@...gle.com>
To:	Andi Kleen <andi@...stfloor.org>
cc:	Ingo Molnar <mingo@...e.hu>, 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
Subject: Re: [patch] x86: reduce srat verbosity in the kernel log

On Wed, 28 Oct 2009, Andi Kleen wrote:

> > +static DECLARE_BITMAP(apicid_map, MAX_LOCAL_APIC) __initdata;
> > +static char apicid_list[MAX_LOCAL_APIC] __initdata;
> 
> Is MAX_LOCAL_APIC really big enough to print them all in ASCII?
> 
> It would be better to not use that large a buffer, but print
> in smaller pieces (I realize this would enlarge your patch,
> but then it would also save a lot of BSS)
> 

MAX_LOCAL_APIC was definitely an arbitrary choice here and has very little 
relevance.  scnlistprintf will protect against overflow, but we still need 
to decide upon a constant that will emit the most information possible 
while not overly polluting the printk and saving on bss, as you mentioned.  
I suspect we could agree on a value as little as 128 and it would work for 
the overwhelming majority (all?) of users.
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