Hi Mel,
On 02/11/2014 07:08 PM, Mel Gorman wrote:
......
I think they should be warned if the ratio is high and have an option of
specifying a ratio manually even if that means that additional nodes
will not be hot-removable.
I think this is easy to do, provide an option for users to specify a
Normal:Movable ratio. This is not phys addr, and it is easy to use.
Yes. It would even be some help if the parameter forced some NUMA nodes
to be Normal instead of Movable regardless of what SRAT says. There
still would be an administrative burden in discovering what nodes are
now pluggable but they must have been dealing with this already.
OK, I will start this work, and send patches soon.
This is all still a kludge around the fact that node memory hot-remove
did not try and cope with full migration by breaking some of the 1:1
virt:phys mapping assumptions when hot-remove was enabled.
I also said before, the implementation now can only be a temporary
solution for memory hotplug since it would take us a lot of time to
deal with 1:1 mapping thing.
But about "breaking some of the 1:1 mapping", would you please give me
any hint of it ? I want to do it too, but I cannot see where to start.
Some hints on how it might be tackled were given back in November 2012
https://lkml.org/lkml/2012/11/29/190 but I never researched it in
detail.
Thank you very much. I will read it one more time, and start trying to
migrate some of the kernel pages first.
Thanks.
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