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Re: [Qemu-devel] [PATCH V17 00/11] Add support for binding guest numa no
From: |
Marcelo Tosatti |
Subject: |
Re: [Qemu-devel] [PATCH V17 00/11] Add support for binding guest numa nodes to host numa nodes |
Date: |
Fri, 6 Dec 2013 16:49:37 -0200 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Fri, Dec 06, 2013 at 10:06:37AM +0100, Paolo Bonzini wrote:
> Il 04/12/2013 08:58, Wanlong Gao ha scritto:
> > According to this patch set, we are able to set guest nodes memory policy
> > like following:
> >
> > -numa node,nodeid=0,cpus=0, \
> > -numa mem,size=1024M,policy=membind,host-nodes=0-1 \
> > -numa node,nodeid=1,cpus=1 \
> > -numa mem,size=1024M,policy=interleave,host-nodes=1
> >
> > This supports
> > "policy={default|membind|interleave|preferred},relative=true,host-nodes=N-N"
> > like format.
> >
> > And add a QMP command "query-numa" to show numa info through
> > this API.
>
> Marcelo, I'm afraid that these NUMA settings complicate getting properly
> aligned pages. If you do something like this:
>
> -numa node,nodeid=0,cpus=0, \
> -numa mem,size=4096M,policy=membind,host-nodes=0 \
> -numa node,nodeid=1,cpus=1 \
> -numa mem,size=4096M,policy=membind,host-nodes=1
>
> You'll have with your patches (without them it's worse of course):
>
> RAM offset physical address node 0
> 0-3840M 0-3840M host node 0
> 4096M-4352M 4096M-4352M host node 0
> 4352M-8192M 4352M-8192M host node 1
> 3840M-4096M 8192M-8448M host node 1
>
> So only 0-3G and 5-8G are aligned, 3G-5G and 8G-8.25G cannot use
> gigabyte pages because they are split across host nodes.
AFAIK the TLB caches virt->phys translations, why specifics of
a given phys address is a factor into TLB caching?
> So rather than your patches, it seems simpler to just widen the PCI hole
> to 1G for i440FX and 2G for q35.
>
> What do you think?
Problem is its a guest visible change. To get 1GB TLB entries with
"legacy guest visible machine types" (which require new machine types
at the host side, but invisible to guest), that won't work.
Windows registration invalidation etc.
But for q35, sure.
- [Qemu-devel] [PATCH V17 07/11] NUMA: expand MAX_NODES from 64 to 128, (continued)
- [Qemu-devel] [PATCH V17 07/11] NUMA: expand MAX_NODES from 64 to 128, Wanlong Gao, 2013/12/04
- [Qemu-devel] [PATCH V17 10/11] NUMA: add qmp command query-numa, Wanlong Gao, 2013/12/04
- [Qemu-devel] [PATCH V17 09/11] NUMA: set guest numa nodes memory policy, Wanlong Gao, 2013/12/04
- [Qemu-devel] [PATCH V17 11/11] NUMA: convert hmp command info_numa to use qmp command query_numa, Wanlong Gao, 2013/12/04
- Re: [Qemu-devel] [PATCH V17 00/11] Add support for binding guest numa nodes to host numa nodes, Paolo Bonzini, 2013/12/06
Re: [Qemu-devel] [PATCH V17 00/11] Add support for binding guest numa nodes to host numa nodes, Paolo Bonzini, 2013/12/06
- Re: [Qemu-devel] [PATCH V17 00/11] Add support for binding guest numa nodes to host numa nodes,
Marcelo Tosatti <=