Re: [RESEND PATCH v7 00/10] Small-sized THP for anonymous memory

[John Hubbard]

On 11/28/23 07:34, Ryan Roberts wrote:
> On 28/11/2023 14:09, David Hildenbrand wrote:
> > On 28.11.23 13:15, Ryan Roberts wrote:
> > > On 28/11/2023 08:48, David Hildenbrand wrote:
> > > How about we just stop trying to come up with a term for the "small-sized THP"
> > > vs "PMD-sized THP" and instead invent a name that covers ALL THP:
> > >
> > > "multi-size THP" vs "PMD-sized THP".
> > >
> > > Then in the docs we can talk about how multi-size THP introduces the ability to
> > > allocate memory in blocks that are bigger than a base page but smaller than
> > > traditional PMD-size, in increments of a power-of-2 number of pages.
> >
> > So you're thinking of something like "multi-size THP" as a feature name, and
> > stating that for now we limit it to <= PMD size. mTHP would be the short name?
>
> Sure.

Sounds workable to me, too.

> > For the stats, we'd document that "AnonHugePages" and friends only count
> > traditional PMD-sized THP for historical reasons -- and that AnonHugePages
> > should have been called AnonHugePmdMapped (which we could still add as an alias
> > and document why AnonHugePages is weird).
>
> Sounds good to me.

OK.

> > Regarding new stats, maybe an interface that indicates the actual sizes would be
> > best. As discussed, extending the existing single-large-file statistics might
> > not be possible and we'd have to come up with a new interface, that maybe
> > completely lacks "AnonHugePages" and directly goes for the individual sizes.
>
> Yes, but I think we are agreed this is future work.

We do want to have at least some way to verify that mTHP is active from
day 0, though.


thanks,
--
John Hubbard
NVIDIA