Re: [PATCH 18/21] x86, numa: Synchronize nid info in memblock.reservewith numa_meminfo.

[Tang Chen]

On 07/24/2013 05:25 AM, Tejun Heo wrote:
> On Fri, Jul 19, 2013 at 03:59:31PM +0800, Tang Chen wrote:
> > Vasilis Liaskovitis found that before we parse SRAT and fulfill numa_meminfo,
> > the nids of all the regions in memblock.reserve[] are MAX_NUMNODES. That is
> > because nids have not been mapped at that time.
> >
> > When we arrange ZONE_MOVABLE in each node later, we need nid in memblock. So
> > after we parse SRAT and fulfill nume_meminfo, synchronize the nid info to
> > memblock.reserve[] immediately.
>
> Having a separate sync is rather nasty.  Why not let
> memblock_set_node() and alloc functions set nid on the reserved
> regions?

Node id and pxm are 1-1 mapped. For the current kernel, before SRAT is 
parsed,
we don't know nid. So all allocated regions are reserved by memblock with
nid = MAX_NUMNODES. So for early allocated memory, we cannot use 
memblock_set_node()
and alloc functions to set the nid.

In this patch-set, we parse SRAT twice, the first one is right after 
memblock is ready.
But we didn't setup nid <-> pxm mapping. So we still have this problem.

And as in [patch 14/21], when reserving hotpluggable memory, we use pxm. 
So my
idea was to do a nid sync in numa_init(). After this, memblock will set 
nid when
it allocates memory.

If we want to let memblock_set_node() and alloc functions set nid on the 
reserved
regions, we should setup nid <-> pxm mapping when we parst SRAT for the 
first time.
If you think this is OK, I can try it.

Thanks.
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