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Date:   Wed, 18 Jan 2023 10:10:44 +0100
From:   Michal Hocko <mhocko@suse.com>
To:     Minchan Kim <minchan@kernel.org>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Suren Baghdasaryan <surenb@google.com>,
        Matthew Wilcox <willy@infradead.org>,
        linux-mm <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>,
        SeongJae Park <sj@kernel.org>
Subject: Re: [PATCH 1/3] mm: return the number of pages successfully paged out
Message-ID: <Y8e3lHsYoWjFWbRU@dhcp22.suse.cz>
References: <20230117231632.2734737-1-minchan@kernel.org>
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On Tue 17-01-23 15:16:30, Minchan Kim wrote:
> The reclaim_pages MADV_PAGEOUT uses needs to return the number of
> pages paged-out successfully, not only the number of reclaimed pages
> in the operation because those pages paged-out successfully will be
> reclaimed easily at the memory pressure due to asynchronous writeback
> rotation(i.e., PG_reclaim with folio_rotate_reclaimable).
> 
> This patch renames the reclaim_pages with paging_out(with hope that
> it's clear from operation point of view) and then adds a additional
> stat in reclaim_stat to represent the number of paged-out but kept
> in the memory for rotation on writeback completion.
> 
> With that stat, madvise_pageout can know how many pages were paged-out
> successfully as well as reclaimed. The return value will be used for
> statistics in next patch.

I really fail to see the reson for the rename and paging_out doesn't
even make much sense as a name TBH.
-- 
Michal Hocko
SUSE Labs