linux-kernel - Re: [PATCH v14 04/15] mm/damon: Adaptively adjust regions

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Message-Id: <1591172518-25575-1-git-send-email-foersleo@amazon.com>
Date:   Wed,  3 Jun 2020 10:21:58 +0200
From:   Leonard Foerster <foersleo@...zon.com>
To:     SeongJae Park <sjpark@...zon.com>
Cc:     akpm@...ux-foundation.org, SeongJae Park <sjpark@...zon.de>,
        Jonathan.Cameron@...wei.com, aarcange@...hat.com, acme@...nel.org,
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Subject: Re: [PATCH v14 04/15] mm/damon: Adaptively adjust regions

On 2020-06-02T15:01:14+02:00 SeongJae Park <sjpark@...zon.com> wrote:

> From: SeongJae Park <sjpark@...zon.de>
> 
> At the beginning of the monitoring, DAMON constructs the initial regions
> by evenly splitting the memory mapped address space of the process into
> the user-specified minimal number of regions.  In this initial state,
> the assumption of the regions (pages in same region have similar access
> frequencies) is normally not kept and thus the monitoring quality could
> be low.  To keep the assumption as much as possible, DAMON adaptively
> merges and splits each region.
> 
> 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 regions if the total number
> of regions is smaller than the half of the user-specified maximum number
> of regions.
> 
> In this way, DAMON provides its best-effort quality and minimal overhead
> while keeping the bounds users set for their trade-off.
> 
> Signed-off-by: SeongJae Park <sjpark@...zon.de>

Reviewed-by: Leonard Foerster <foersleo@...zon.de>