Re: [PATCH part5 0/7] Arrange hotpluggable memory as ZONE_MOVABLE.

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

On 08/12/2013 01:54 PM, Tejun Heo wrote:
> Hello, Tony.
> 
> On Mon, Aug 12, 2013 at 08:49:42PM +0000, Luck, Tony wrote:
>> The only fly I see in the ointment here is the crazy fragmentation of physical
>> memory below 4G on X86 systems.  Typically it will all be on the same node.
>> But I don't know if there is any specification that requires it be that way. If some
>> "helpful" OEM decided to make some "lowmem" (below 4G) be available on
>> every node, they might in theory do something truly awesomely strange.  But
>> even here - the granularity of such mappings tends to be large enough that
>> the "allocate near where the kernel was loaded" should still work to make those
>> allocations be on the same node for the "few megabytes" level of allocations.
> 
> Yeah, "near kernel" allocations are needed only till SRAT information
> is parsed and fed into memblock.  From then on, it'll be the usual
> node-affine top-down allocations, so the memory amount of interest
> here is inherently tiny; otherwise, we're doing something silly in our
> boot sequence.
> 

Again, how much memory are we talking about here?

	-hpa


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