Re: [PATCH part4 4/4] x86, acpi, numa, mem_hotplug: Find hotpluggable memory in SRAT memory affinities.

[Yinghai Lu <yinghai@kernel.org>]

On Fri, Aug 9, 2013 at 4:43 PM, H. Peter Anvin <hpa@zytor.com> wrote:
> On 08/09/2013 04:39 PM, Yinghai Lu wrote:
>>>>
>>>> Also parse srat table two times looks silly.
>>>
>>> By parsing SRAT twice, I can avoid memory allocation for acpi_tables_addr
>>> in acpi_initrd_override_copy() procedure at such an early time. This memory
>>> could also be in hotpluggable area.
>>
>> You already mark kernel position to be not hot-plugged,  so near the
>> kernel range should be safe to be put override acpi tables.
>>
>> also what I mean parse srat two times:
>> parse to get hotplug range, and late parse other numa info again.
>>
>
> Doing two passes over a small data structure (SRAT) would seem more
> sensible than allocating memory just to avoid that...

for x86 there is some numa info discovery path, and there are chance
srat is wrong but still have hotplug range there, or numa finally is using other
way or not used. Inconsistency looks weird.

numa_meminfo is static struct, we have way to get final numa info early enough
before we need use memblock to alloc buffer with it.

Yinghai

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