Re: [LSF/MM/BPF TOPIC] BoF VM live migration over CXL memory​

[Dragan Stancevic <dragan@stancevic.com>]

On 4/11/23 01:37, Huang, Ying wrote:
> Gregory Price <gregory.price@memverge.com> writes:
> 
> [snip]
> 
>> 2. During the migration process, the memory needs to be forced not to be
>>     migrated to another node by other means (tiering software, swap,
>>     etc).  The obvious way of doing this would be to migrate and
>>     temporarily pin the page... but going back to problem #1 we see that
>>     ZONE_MOVABLE and Pinning are mutually exclusive.  So that's
>>     troublesome.
> 
> Can we use memory policy (cpusets, mbind(), set_mempolicy(), etc.) to
> avoid move pages out of CXL.mem node?  Now, there are gaps in tiering,
> but I think it is fixable.


Hmmm, I don't know about cpusets. For mbind, are you thinking something 
along the lines of MPOL_MF_MOVE_ALL? I guess it does have that 
deterministic placement, but this would have to be called from the 
process itself. Unlike migrate_pages which takes a pid.

Same for set_mempolicy, right?

I mean I guess, if some of this needs to be added into qemu it's not the 
end of the word...


> Best Regards,
> Huang, Ying
> 
> [snip]
> 

-- 
--
Peace can only come as a natural consequence
of universal enlightenment -Dr. Nikola Tesla