From: Randy Dunlap <randy.dunlap@oracle.com>
To: "Frank A. Kingswood" <frank@kingswood-consulting.co.uk>
Cc: linux-kernel@vger.kernel.org
Subject: Re: NR_CPUS configuration option wrong
Date: Thu, 20 May 2010 11:35:25 -0700 [thread overview]
Message-ID: <4BF580ED.3080207@oracle.com> (raw)
In-Reply-To: <4BF58054.8060601@kingswood-consulting.co.uk>
On 05/20/10 11:32, Frank A. Kingswood wrote:
> Randy Dunlap wrote:
>> On Thu, 20 May 2010 18:34:32 +0100 Frank A. Kingswood wrote:
>>
>>> Hi!
>>>
>>> The configuration MAXSMP help text indicates it is used to enable
>>> configuration of number of CPUs. However, NR_CPUS depends on !MAXSMP.
>>>
>>> arch/x86/Kconfig:
>>> 758 config NR_CPUS
>>> 759 int "Maximum number of CPUs" if SMP && !MAXSMP
>>
>> That line depends on !MAXSMP. Then below there, we find:
>>
>> default "4096" if MAXSMP
>
> Hah, weird.
> I can see now it is possible to parse the MAXSMP help this way, but it
> was not obvious.
Ambiguity is fairly easy. :(
> In menuconfig you see two questions:
>
> [ ] Configure Maximum number of SMP Processors and NUMA Nodes
> [8] Maximum number of CPUs
>
> and setting the first one YES makes the second one go away.
>
> Perhaps restating the help as "Set number of SMP processors and NUMA
> nodes to the maximum that the kernel supports" might help.
Yes, that sounds better. Want to submit a patch for that?
--
~Randy
*** Remember to use Documentation/SubmitChecklist when testing your code ***
prev parent reply other threads:[~2010-05-20 18:36 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-20 17:34 NR_CPUS configuration option wrong Frank A. Kingswood
2010-05-20 17:38 ` Randy Dunlap
2010-05-20 18:32 ` Frank A. Kingswood
2010-05-20 18:35 ` Randy Dunlap [this message]
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