linux-kernel - Re: [PATCH 3/6] INIT: Limit the number of per cpu calibration bootup messages

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Date:	Tue, 17 Nov 2009 18:59:46 +0300
From:	Cyrill Gorcunov <gorcunov@...il.com>
To:	David Miller <davem@...emloft.net>
Cc:	hpa@...or.com, mingo@...e.hu, travis@....com, tglx@...utronix.de,
	akpm@...ux-foundation.org, heiko.carstens@...ibm.com,
	rdreier@...co.com, rdunlap@...otime.net, tj@...nel.org,
	andi@...stfloor.org, gregkh@...e.de, yhlu.kernel@...il.com,
	rientjes@...gle.com, rostedt@...dmis.org, rusty@...tcorp.com.au,
	seto.hidetoshi@...fujitsu.com, steiner@....com, fweisbec@...il.com,
	x86@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/6] INIT: Limit the number of per cpu calibration
	bootup messages

On Mon, Nov 16, 2009 at 07:09:22PM -0800, David Miller wrote:
...
> >
> > IA-64 and SPARC already has this variable. But boot_cpu_id() as an
> > inline function seem to be more natural/portable ineed.
> 
> Only 32-bit SPARC actually has it.  On sparc64 we have no reason to
> remember which processor was the boot cpu, and remembering it merely
> for the sake of only printing out the bogomips message once seems a
> bit excessive?
> 
> How about:
> 
> 	static bool printed;
> 
> 	if (!printed) {
> 		printk(...);
> 		printed = true;
> 	}
> 
> Or, alternatively, use an atomic_t instead of a bool if you think
> races matter this early in the boot process.
> 

Hi David,

I must admit I know *nothing* about SPARC code. I was rather pointing
out that some archs already use this variable.  IOW it means
that per-platform boot_cpu_id() helper implementation may be not
that simple. Perhaps for other archs like SPARC64, where as you
said no need to remember boot cpu id at all, we should define
some __weak per-kernel global helper which would return 0
and every arch would implement own helper boot_cpu_id().

	-- Cyrill
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