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From:   Yu Zhao <yuzhao@google.com>
Date:   Wed, 21 Jun 2023 12:48:22 -0600
Message-ID: <CAOUHufbb9_Cah6tT61+WKfM0T9CDmkZ5zym=MuHj2YVsgh-hiw@mail.gmail.com>
Subject: Re: [RFC PATCH v2 0/6] mm: working set reporting
To:     Yuanchu Xie <yuanchu@google.com>
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "Rafael J . Wysocki" <rafael@kernel.org>,
        "Michael S . Tsirkin" <mst@redhat.com>,
        David Hildenbrand <david@redhat.com>,
        Jason Wang <jasowang@redhat.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Michal Hocko <mhocko@kernel.org>,
        Roman Gushchin <roman.gushchin@linux.dev>,
        Shakeel Butt <shakeelb@google.com>,
        Muchun Song <muchun.song@linux.dev>,
        Kefeng Wang <wangkefeng.wang@huawei.com>,
        Kairui Song <kasong@tencent.com>,
        Yosry Ahmed <yosryahmed@google.com>,
        "T . J . Alumbaugh" <talumbau@google.com>,
        Wei Xu <weixugc@google.com>, SeongJae Park <sj@kernel.org>,
        Sudarshan Rajagopalan <quic_sudaraja@quicinc.com>,
        kai.huang@intel.com, hch@lst.de, jon@nutanix.com,
        Aneesh Kumar K V <aneesh.kumar@linux.ibm.com>,
        Matthew Wilcox <willy@infradead.org>,
        Vasily Averin <vasily.averin@linux.dev>,
        linux-kernel@vger.kernel.org,
        virtualization@lists.linux-foundation.org, linux-mm@kvack.org,
        cgroups@vger.kernel.org
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On Wed, Jun 21, 2023 at 12:16=E2=80=AFPM Yuanchu Xie <yuanchu@google.com> w=
rote:
>
> RFC v1: https://lore.kernel.org/linux-mm/20230509185419.1088297-1-yuanchu=
@google.com/
> For background and interfaces, see the RFC v1 posting.

v1 only mentioned one use case (ballooning), but we both know there
are at least two solid use cases (the other being job
scheduling/binpacking, e.g., for kubernetes [1]).

Please do a survey, as thoroughly as possible, of use cases.
* What's the significance of WSR to the landscape, in terms of server
and client use cases?
* How would userspace tools, e.g., a PMU-based memory profiler,
leverage the infra provided by WSR?
* Would those who register slab shrinkers, e.g., DMA buffs [2], want
to report their working sets?
* Does this effort intersect with memory placement with NUMA and CXL.mem?

[1] https://kubernetes.io/docs/concepts/configuration/manage-resources-cont=
ainers/
[2] https://lore.kernel.org/linux-mm/20230123191728.2928839-1-tjmercier@goo=
gle.com/