Re: sched: CPU #1's llc-sibling CPU #0 is not on the same node!

[Yasuaki Ishimatsu]

2013/02/27 14:11, Yinghai Lu wrote:
> On Tue, Feb 26, 2013 at 8:43 PM, Yasuaki Ishimatsu
> <isimatu.yasuaki@xxxxxxxxxxxxxx> wrote:
> > 2013/02/27 13:04, Yinghai Lu wrote:
> > > On Tue, Feb 26, 2013 at 7:38 PM, Yasuaki Ishimatsu
> > > <isimatu.yasuaki@xxxxxxxxxxxxxx> wrote:
> > > > 2013/02/27 11:30, Yinghai Lu wrote:
> > > > > Do you mean you can not boot one socket system with 1G ram ?
> > > > > Assume socket 0 does not support hotplug, other 31 sockets support hot
> > > > > plug.
> > > > >
> > > > > So we could boot system only with socket0, and later one by one hot
> > > > > add other cpus.
> > > >
> > > >
> > > >
> > > > In this case, system can boot. But other cpus with bunch of ram hot
> > > > plug may fails, since system does not have enough memory for cover
> > > > hot added memory. When hot adding memory device, kernel object for the
> > > > memory is allocated from 1G ram since hot added memory has not been
> > > > enabled.
> > >
> > > yes, it may fail, if the one node memory need page table and vmemmap
> > > is more than 1g ...

> > > for hot add memory we need to
> > > 1. add another wrapper for init_memory_mapping, just like
> > > init_mem_mapping() for booting path.
> > > 2. we need make memblock more generic, so we can use it with hot add
> > > memory during runtime.
> > > 3. with that we can initialize page table for hot added node with ram.
> > > a. initial page table for 2M near node top is from node0 ( that does
> > > not support hot plug).
> > > b. then will use 2M for memory below node top...
> > > c. with that we will make sure page table stay on local node.
> > >    alloc_low_pages need to be updated to support that.
> > > 4. need to make sure vmemmap on local node too.
> >
> >
> > I think so too. By this, memory hot plug becomes more useful.

I agree with your idea. But I think above ideas is future work.
So at first we should use movable memory for memory hot plug.
After that, we will implement above ideas.

> > > so hot-remove node will work too later.
> > >
> > > In the long run, we should make booting path and hot adding more
> > > similar and share at most code.
> > > That will make code get more test coverage.
>
> Tang,  Yasuaki, Andrew,
>
> Please check if you are ok with attached reverting patch.

We will fix this problem with no objection. So please wait a while.

And the problem occurs by "movablemem_map=srat" not "movablemem_map=nn[KMG]@ss[KMG]"
At least, if you want to revert it, you should revert only "movablemem_map=srat" part.

Thanks,
Yasuaki Ishimatsu  

> Tim, Don,
> Can you try if attached reverting patch fix all the problems for you ?
>
> Thanks
>
> Yinghai


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