Re: [PATCH] mm: add zblock allocator

[Nhat Pham <nphamcs@gmail.com>]

On Tue, Apr 1, 2025 at 11:45 PM <igor.b@beldev.am> wrote:
>
> Hi Shakeel,
>
> 2025-04-02 03:16 Shakeel Butt wrote:
> > Hi Vitaly,
> >
> > On Tue, Apr 01, 2025 at 07:17:54PM +0200, Vitaly Wool wrote:
> >> zblock is a special purpose allocator for storing compressed pages.
> >> It stores integer number of compressed objects per its block. These
> >> blocks consist of several physical pages (2**n, i. e. 1/2/4/8).
> >>
> >> With zblock, it is possible to densely arrange objects of various
> >> sizes
> >> resulting in low internal fragmentation. Also this allocator tries to
> >> fill incomplete blocks instead of adding new ones,  in many cases
> >> providing a compression ratio substantially higher than z3fold and
> >> zbud
> >> (though lower than zmalloc's).
> >>
> >> zblock does not require MMU
> >
> > Can you explain why not requiring MMU is important for your use-case?
> > Also what exactly is your use-case? Are you planning to use zblock
> > through zram or zswap or something new?
>
> We have 2 use cases for a zpool backend: data centers (zswap) and small
> MMU less devices, this is where zram comes ito play. We know that zram
> over zpool patch is still out of tree but we also know the story behind
> that :)

In the upstream tree, zram also depends on MMU. It is probably
different in your private tree, but please keep the conversation and
documentation aligned with the reality of upstream :)