Re: [PATCH] util: NUMA aware memory preallocation

[Daniel P . Berrangé]

On Wed, May 11, 2022 at 11:31:23AM +0200, David Hildenbrand wrote:
> >> Long story short, management application has no way of learning
> >> TIDs of allocator threads so it can't make them run NUMA aware.
> > 
> > This feels like the key issue. The preallocation threads are
> > invisible to libvirt, regardless of whether we're doing coldplug
> > or hotplug of memory-backends. Indeed the threads are invisible
> > to all of QEMU, except the memory backend code.
> > 
> > Conceptually we need 1 or more explicit worker threads, that we
> > can assign CPU affinity to, and then QEMU can place jobs on them.
> > I/O threads serve this role, but limited to blockdev work. We
> > need a generalization of I/O threads, for arbitrary jobs that
> > QEMU might want to farm out to specific numa nodes.
> 
> At least the "-object iothread" thingy can already be used for actions
> outside of blockdev. virtio-balloon uses one for free page hinting.

Ah that's good to know, so my idea probably isn't so much work as
I thought it might be.


With regards,
Daniel
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