Re: [patch] slab: add memory hotplug support

[KAMEZAWA Hiroyuki]

On Tue, 2 Mar 2010 18:39:20 -0800 (PST)
David Rientjes <rientjes@xxxxxxxxxx> wrote:

> On Wed, 3 Mar 2010, KAMEZAWA Hiroyuki wrote:
> 
> > At node hot-add
> > 
> >  * pgdat is allocated from other node (because we have no memory for "nid")
> >  * memmap for the first section (and possiby others) will be allocated from
> >    other nodes.
> >  * Once a section for the node is onlined, any memory can be allocated localy.
> > 
> 
> Correct, and the struct kmem_list3 is also alloacted from other nodes with 
> my patch.
> 
> >    (Allocating memory from local node requires some new implementation as
> >     bootmem allocater, we didn't that.)
> > 
> >  Before this patch, slab's control layer is allocated by cpuhotplug.
> >  So, at least keeping this order,
> >     memory online -> cpu online
> >  slab's control layer is allocated from local node.
> > 
> >  When node-hotadd is done in this order
> >     cpu online -> memory online
> >  kmalloc_node() will allocate memory from other node via fallback.
> > 
> >  After this patch, slab's control layer is allocated by memory hotplug.
> >  Then, in any order, slab's control will be allocated via fallback routine.
> > 
> 
> Again, this addresses memory hotplug that requires a new node to be 
> onlined that do not have corresponding cpus that are being onlined.  On 
> x86, these represent ACPI_SRAT_MEM_HOT_PLUGGABLE regions that are onlined 
> either by the acpi hotplug or done manually with CONFIG_ARCH_MEMORY_PROBE.  
> On other architectures such as powerpc, this is done in different ways.
> 
> All of this is spelled out in the changelog for the patch.
> 
Ah, ok. for cpu-less node and kmallco_node() against that node.

Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>

Thanks,
-Kame



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