Re: [RFC PATCH v2 0/5] Reduce NUMA balance caused TLB-shootdowns in a VM

[John Hubbard]

On 8/14/23 02:09, Yan Zhao wrote:
...
> > hmm_range_fault()-based memory management in particular might benefit
> > from having NUMA balancing disabled entirely for the memremap_pages()
> > region, come to think of it. That seems relatively easy and clean at
> > first glance anyway.
> >
> > For other regions (allocated by the device driver), a per-VMA flag
> > seems about right: VM_NO_NUMA_BALANCING ?
> Thanks a lot for those good suggestions!
> For VMs, when could a per-VMA flag be set?
> Might be hard in mmap() in QEMU because a VMA may not be used for DMA until
> after it's mapped into VFIO.
> Then, should VFIO set this flag on after it maps a range?
> Could this flag be unset after device hot-unplug?

I'm hoping someone who thinks about VMs and VFIO often can chime in.


thanks,
--
John Hubbard
NVIDIA