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From:   Chris Li <chrisl@kernel.org>
Date:   Fri, 8 Dec 2023 16:09:51 -0800
Message-ID: <CAF8kJuMt7_6_8JTNA5UJkhy3Drw6=802wbwXbvUn+hafmsFA7Q@mail.gmail.com>
Subject: Re: [PATCH v6] zswap: memcontrol: implement zswap writeback disabling
To:     Yosry Ahmed <yosryahmed@google.com>
Cc:     Nhat Pham <nphamcs@gmail.com>, akpm@linux-foundation.org,
        tj@kernel.org, lizefan.x@bytedance.com, hannes@cmpxchg.org,
        cerasuolodomenico@gmail.com, sjenning@redhat.com,
        ddstreet@ieee.org, vitaly.wool@konsulko.com, mhocko@kernel.org,
        roman.gushchin@linux.dev, shakeelb@google.com,
        muchun.song@linux.dev, hughd@google.com, corbet@lwn.net,
        konrad.wilk@oracle.com, senozhatsky@chromium.org, rppt@kernel.org,
        linux-mm@kvack.org, kernel-team@meta.com,
        linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
        david@ixit.cz
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Hi Yosry,

On Thu, Dec 7, 2023 at 5:12=E2=80=AFPM Yosry Ahmed <yosryahmed@google.com> =
wrote:
> > I briefly summarized my recent discussion with Johannes here:
> >
> > https://lore.kernel.org/all/CAKEwX=3DNwGGRAtXoNPfq63YnNLBCF0ZDOdLVRsvzU=
mYhK4jxzHA@mail.gmail.com/
> >
> > TL;DR is we acknowledge the potential usefulness of swap.tiers
> > interface, but the use case is not quite there yet, so it does not
> > make too much sense to build up that heavy machinery now.
> > zswap.writeback is a more urgent need, and does not prevent swap.tiers
> > if we do decide to implement it.
>
> I am honestly not convinced by this. There is no heavy machinery here.
> The interface is more generic and extensible, but the implementation
> is roughly the same. Unless we have a reason to think a swap.tiers
> interface may make it difficult to extend this later or will not
> support some use cases, I think we should go ahead with it. If we are
> worried that "tiers" may not accurately describe future use cases, we
> can be more generic and call it swap.types or something.
>
+100.

Chris