Subject: Re: [PATCH v2 3/5] x86: Kconfig: Remove CONFIG_NODES_SPAN_OTHER_NODES

From: Hoan Tran OS <[email-masked]>
Date: Tue, 6 Aug 2019 16:47:12 +0000

Hi Thomas,

On 7/15/19 11:43 AM, Thomas Gleixner wrote:
> On Thu, 11 Jul 2019, Hoan Tran OS wrote:
> 
>> Remove CONFIG_NODES_SPAN_OTHER_NODES as it's enabled
>> by default with NUMA.
> 
> As I told you before this does not mention that the option is now enabled
> even for x86(32bit) configurations which did not enable it before and does
> not longer depend on X86_64_ACPI_NUMA.

Agreed, let me add it into this patch description.

> 
> And there is still no rationale why this makes sense.
> 

As we know about the memmap_init_zone() function, it is used to 
initialize all pages. During initializing, early_pfn_in_nid() function 
makes sure the page is in the same node id. Otherwise, 
memmap_init_zone() only checks the page validity. It won't work with 
node memory spans across the others.

The option CONFIG_NODES_SPAN_OTHER_NODES is only used to enable 
early_pfn_in_nid() function.

It occurs during boot-time and won't affect the run-time performance.
And I saw the majority NUMA architectures enable this option by default 
with NUMA.

Thanks and Regards
Hoan

> Thanks,
> 	tglx
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