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Date:   Thu, 30 Nov 2023 14:47:43 -0500
From:   Dan Schatzberg <schatzberg.dan@gmail.com>
To:     Johannes Weiner <hannes@cmpxchg.org>
Cc:     Michal Hocko <mhocko@suse.com>,
        Roman Gushchin <roman.gushchin@linux.dev>,
        Yosry Ahmed <yosryahmed@google.com>, Huan Yang <link@vivo.com>,
        linux-kernel@vger.kernel.org, cgroups@vger.kernel.org,
        linux-mm@kvack.org, Shakeel Butt <shakeelb@google.com>,
        Muchun Song <muchun.song@linux.dev>,
        Andrew Morton <akpm@linux-foundation.org>,
        David Hildenbrand <david@redhat.com>,
        Matthew Wilcox <willy@infradead.org>,
        Huang Ying <ying.huang@intel.com>,
        Kefeng Wang <wangkefeng.wang@huawei.com>,
        Peter Xu <peterx@redhat.com>,
        "Vishal Moola (Oracle)" <vishal.moola@gmail.com>,
        Yue Zhao <findns94@gmail.com>, Hugh Dickins <hughd@google.com>
Subject: Re: [PATCH 0/1] Add swappiness argument to memory.reclaim
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On Thu, Nov 30, 2023 at 11:56:42AM -0500, Johannes Weiner wrote:
> [...]
> So I wouldn't say it's merely a reclaim hint. It controls a very
> concrete and influential factor in VM decision making. And since the
> global swappiness is long-established ABI, I don't expect its meaning
> to change significantly any time soon.

I want to add to this last point. While swappiness does not have
terribly well-defined semantics - it is the (only?) existing mechanism
to control balance between anon and file reclaim. I'm merely
advocating for the ability to adjust swappiness during proactive
reclaim separately from reactive reclaim. To what degree the behavior
and semantics of swappiness change is a bit orthogonal here.