On Sun, Jan 14, 2024 at 2:42 PM Nhat Pham [off-list ref] wrote:

On Sun, Jan 14, 2024 at 10:49 AM Yosry Ahmed [off-list ref] wrote:

quoted

On Fri, Jan 12, 2024 at 4:38 PM Nhat Pham [off-list ref] wrote:

quoted

On Fri, Jan 12, 2024 at 3:37 PM Yosry Ahmed [off-list ref] wrote:

quoted

On Fri, Jan 12, 2024 at 11:42 AM Nhat Pham [off-list ref] wrote:

quoted

On Fri, Jan 12, 2024 at 11:31 AM Yosry Ahmed [off-list ref] wrote:

quoted

The z3fold compressed pages allocator is not widely used, most users use
zsmalloc. The only disadvantage of zsmalloc in comparison is the
dependency on MMU, and zbud is a more common option for !MMU as it was
the default zswap allocator for a long time.

Johannes and I were chatting about this the other day. We might be
able to disable certain zsmalloc behavior in the case of !MMU, making
it available there too. Once that's happened, we can outright remove
z3fold and zbud, and have one allocator to rule them all? :)

(Adding Sergey and Minchan for visibility)

I didn't want to bring up the zsmalloc MMU dependency in this thread
to reduce noise, but that's also what I had in mind. Sergey and I were
also chatting about this the other day :)

I thought deprecating z3fold is the low hanging fruit. Then, once we
can sort out the MMU dependency in zsmalloc, we can go after zbud as
well.

Makes sense to me. Should we do the same thing to zbud? We probably
have even less of a case for it, no?

Do you mean declare it as deprecated now? I initially thought that
would only be appropriate to do after zsmalloc has no dependency on
MMU, so that we can confidently say zbud has no practical use case.

Ah, I misread your email. My bad. Personally, I'd like to declare both
(zbud and z3fold) as deprecated. That said, no strong feelings here -
as long as (eventually) we move towards retiring both of them. So my
original ACK still holds.

Not entirely sure which should we remove first between zbud and z3fold
though. I was under the assumption that z3fold is slightly better, but
that could be my bias for shiny new things showing :)

My rationale is that zbud was the default zswap allocator for a long
time, so it's the one we should keep for now as it is more likely to
have users. That said, I don't know of any users of either zbud or
z3fold, and I am fine starting with deprecating either.