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

["H. Peter Anvin" <hpa@zytor.com>]

On 08/09/2013 04:53 PM, Yinghai Lu wrote:
> 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.
> 

Now, for kernel-generated data if you can define a sensible maximum you
can put it in brk, if not, you have a serious problem.

	-hpa


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