Re: [Qemu-devel] [RFC PATCH 14/14] numa: add -numa node, memdev= option

[Paolo Bonzini]

Il 11/12/2013 16:36, Igor Mammedov ha scritto:
>> >  -object memory-ram,size=1024M,policy=membind,host-nodes=0,id=ram-node0 \
>> >  -numa node,nodeid=0,cpus=0,memdev=ram-node0 \
>> >  -object 
>> > memory-ram,size=1024M,policy=interleave,host-nodes=1-3,id=ram-node1 \
>> >  -numa node,nodeid=1,cpus=1,memdev=ram-node1
> 
> I was thinking about a bit more radical change:
> -object memory-ram,size=1024M,policy=membind,host-nodes=0,id=ram-node0
> -device dimm,memdev=ram-node0,node=0
> -object memory-ram,size=1024M,policy=membind,host-nodes=1,id=ram-node1
> -device dimm,memdev=ram-node1,node=1
> 
> that would allow to avoid synthetic -numa option

You still need -numa for cpus, at least in the short/medium-term.

> but would require conversion
> of initial RAM to dimms. That would be more flexible for example allowing
> bind several backends to one node (like: 1Gb_hugepage + 2Mb_hugepage ones)

Yes, that's another possibility, perhaps even cleaner.

With "-numa node,memdev=", your board only needs to use
memory_region_allocate_system_memory in order to apply a NUMA policy to
guest RAM; it also works with guests or boards that are not themselves
NUMA-aware.

Doing the same with "-device dimm" requires changing the board to
support RAM-as-dimms; do you have any idea how easy/hard that would be?

Paolo