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From:   Zhongkun He <hezhongkun.hzk@bytedance.com>
Date:   Tue, 12 Dec 2023 10:43:38 +0800
Message-ID: <CACSyD1NPM-m_KeViGdoDbaoAwKUETkYPe8f6HLEzRtLm8VE+Fg@mail.gmail.com>
Subject: Re: [External] Re: [PATCH v6] zswap: memcontrol: implement zswap
 writeback disabling
To:     Minchan Kim <minchan@kernel.org>
Cc:     Johannes Weiner <hannes@cmpxchg.org>, Chris Li <chrisl@kernel.org>,
        Nhat Pham <nphamcs@gmail.com>, akpm@linux-foundation.org,
        tj@kernel.org, lizefan.x@bytedance.com,
        cerasuolodomenico@gmail.com, yosryahmed@google.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, Kairui Song <kasong@tencent.com>
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> Hi Johannes,
>
> I haven't been following the thread closely, but I noticed the discussion
> about potential use cases for zram with memcg.
>
> One interesting idea I have is to implement a swap controller per cgroup.
> This would allow us to tailor the zram swap behavior to the specific needs of
> different groups.

Hi Minchan,

It would be great if this feature could be in place. We are using zram and also
trying to use zswap to offload memory to disk. As kairui mentioned above,
there are many workloads of varying priority and sensitivity on a machine.

>
> For example, Group A, which is sensitive to swap latency, could use zram swap
> with a fast compression setting, even if it sacrifices some compression ratio.
> This would prioritize quick access to swapped data, even if it takes up more space.
>
> On the other hand, Group B, which can tolerate higher swap latency, could benefit
> from a slower compression setting that achieves a higher compression ratio.
> This would maximize memory efficiency at the cost of slightly slower data access.
>
> This approach could provide a more nuanced and flexible way to manage swap usage
> within different cgroups.

Indeed.