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From:   Shakeel Butt <shakeelb@google.com>
Date:   Wed, 25 Nov 2020 07:29:41 -0800
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Subject: Re: [PATCH v22 03/18] mm/damon: Adaptively adjust regions
To:     SeongJae Park <sjpark@amazon.com>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
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On Tue, Oct 20, 2020 at 2:01 AM SeongJae Park <sjpark@amazon.com> wrote:
>
> From: SeongJae Park <sjpark@amazon.de>
>
> Even somehow the initial monitoring target regions are well constructed
> to fulfill the assumption (pages in same region have similar access
> frequencies), the data access pattern can be dynamically changed.  This
> will result in low monitoring quality.  To keep the assumption as much
> as possible, DAMON adaptively merges and splits each region based on
> their access frequency.
>
> For each ``aggregation interval``, it compares the access frequencies of
> adjacent regions and merges those if the frequency difference is small.
> Then, after it reports and clears the aggregated access frequency of
> each region, it splits each region into two or three regions if the
> total number of regions will not exceed the user-specified maximum
> number of regions after the split.
>
> In this way, DAMON provides its best-effort quality and minimal overhead
> while keeping the upper-bound overhead that users set.
>
> Signed-off-by: SeongJae Park <sjpark@amazon.de>
> Reviewed-by: Leonard Foerster <foersleo@amazon.de>

The high level comment I have is that kdamond_[merge|split]_regions
should be part of the abstraction of the target instead of the damon
context.