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Date:   Thu, 30 Nov 2023 14:50:54 -0500
From:   Dan Schatzberg <schatzberg.dan@gmail.com>
To:     Shakeel Butt <shakeelb@google.com>
Cc:     Johannes Weiner <hannes@cmpxchg.org>,
        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, Michal Hocko <mhocko@kernel.org>,
        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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 <20231130184424.7sbez2ukaylerhy6@google.com>
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On Thu, Nov 30, 2023 at 06:44:24PM +0000, Shakeel Butt wrote:
> [...]
> > * Swapout should be limited to manage SSD write endurance. In near-OOM
> 
> Is this about swapout to SSD only?

Correct

> >   situations we are fine with lots of swap-out to avoid OOMs. As these are
> >   typically rare events, they have relatively little impact on write endurance.
> >   However, proactive reclaim runs continuously and so its impact on SSD write
> >   endurance is more significant. Therefore it is desireable to control swap-out
> >   for proactive reclaim separately from reactive reclaim
> 
> This is understandable but swapout to zswap should be fine, right?
> (Sorry I am not following the discussion on zswap patches from Nhat. Is
> the answer there?)

You're correct here as well - we're not concerned about swapout to
zswap as that does not impact SSD write endurance. This is not related
to Nhat's patches.