linux-kernel - Re: [PATCH] x86: allow 8 more cpus could be used

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Message-ID: <49823869.4010406@oracle.com>
Date:	Thu, 29 Jan 2009 15:14:49 -0800
From:	Randy Dunlap <randy.dunlap@...cle.com>
To:	Ingo Molnar <mingo@...e.hu>
CC:	Randy Dunlap <randy.dunlap@...cle.com>,
	Yinghai Lu <yinghai@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86: allow 8 more cpus could be used

Ingo Molnar wrote:
> * Randy Dunlap <randy.dunlap@...cle.com> wrote:
> 
>> Ingo Molnar wrote:
>>> * Yinghai Lu <yinghai@...nel.org> wrote:
>>>
>>>> Impact: fix left out MARCO
>>>>
>>>> X86_PC will be always enabled. so need to check if we have bigsmp 
>>>> support built in before cut off more than 8 cpus.
>>> ah, that's a leftover reference to X86_PC. It can now be removed, together 
>>> with the Kconfig X86_PC option.
>>>
>>>> -#if defined(CONFIG_X86_PC) && defined(CONFIG_X86_32)
>>>> +#if defined(CONFIG_X86_PC) && !defined(CONFIG_X86_BIGSMP)
>>>>  	if (def_to_bigsmp && nr_cpu_ids > 8) {
>>>>  		unsigned int cpu;
>>>>  		unsigned nr;
>>> Could you please send a patch that removes both X86_PC and X86_BIGSMP - 
>>> and removes the above cutoff code too, so that it will be built-in all the 
>>> time?
>> and at what cost, please?
> 
> the size difference between a bigsmp and a normal-smp x86 defconfig kernel 
> is 0.011%. Zero difference on a UP kernel. (And UP is what most of the 
> ultra-embedded systems are using)

That's static size?  how about cpu and apic table space?


Thanks,
-- 
~Randy
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