Re: [FYI] DAMON and virtio-balloon in DeepSeek's DSec paper

[Gao Xiang <xiang@kernel.org>]

On Wed, Sep 30, 2026 at 05:37:11PM +0800, Muchun Song wrote:
> 

...

> 
> > 
> > Anyway, it'd be better to get some numbers with RL or agent workloads
> > (especially the host memory is under reasonable pressure) before
> > landing all these new infras upstream if proceeding in this way.
> 
> At least for now, as far as I'm concerned, I don't intend to land all the
> features mentioned here. The first thing I want to address is on-demand
> allocation of struct page.

From my point of view, on-demend allocation of `struct page` for FSDAX
is indeed useful and can be landed upstream, mainly because `struct page`
initialization takes much long time for large FSDAX devices even a small
range is used, that impacts the guest startup time a lot.

But in order to make it safe for production, I suggest reserve the
guest memory in advance for the worst cases of `struct page` at the first
stage, otherwise it could cause unexpected issues for many guest workloads:
it's hard to perdict if the guest memory is still enough, it's unfriendly
to system designers as well (that would completely based on their
experience and hard to ensure the service quality beforehand.)

Since the guest memory for `struct page` is touched on-demand, the memory
over-committing on the host is still workable, the memory reservation
can be removed after the reclaim path is done.

Thanks,
Gao Xiang


> 
> Thanks,
> Muchun
> 
> > 
> > Thanks,
> > Gao Xiang
> 
>