Re: [PATCH v3 0/5] add persistent huge zero folio support

[Kiryl Shutsemau]

On Mon, Aug 11, 2025 at 12:21:23PM +0200, David Hildenbrand wrote:
> On 11.08.25 12:17, Kiryl Shutsemau wrote:
> > On Mon, Aug 11, 2025 at 11:09:24AM +0100, Lorenzo Stoakes wrote:
> > > On Mon, Aug 11, 2025 at 11:07:48AM +0100, Kiryl Shutsemau wrote:
> > > > 
> > > > Well, my worry is that 2M can be a high tax for smaller machines.
> > > > Compile-time might be cleaner, but it has downsides.
> > > > 
> > > > It is also not clear if these users actually need physical HZP or virtual
> > > > is enough. Virtual is cheap.
> > > 
> > > The kernel config flag (default =N) literally says don't use unless you
> > > have plenty of memory :)
> > > 
> > > So this isn't an issue.
> > 
> > Distros use one-config-fits-all approach. Default N doesn't help
> > anything.
> 
> You'd probably want a way to say "use the persistent huge zero folio if you
> machine has more than X Gigs". That's all reasonable stuff that can be had
> on top of this series.

We have 'totalram_pages() < (512 << (20 - PAGE_SHIFT))' check in
hugepage_init(). It can [be abstracted out and] re-used.

-- 
Kiryl Shutsemau / Kirill A. Shutemov