linux-kernel - Re: [PATCH 0/2] mm/damon: introduce DAMOS filter type for active pages

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Message-Id: <20250318185156.35448-1-sj@kernel.org>
Date: Tue, 18 Mar 2025 11:51:56 -0700
From: SeongJae Park <sj@...nel.org>
To: Nhat Pham <nphamcs@...il.com>
Cc: SeongJae Park <sj@...nel.org>,
	akpm@...ux-foundation.org,
	corbet@....net,
	linux-mm@...ck.org,
	kernel-team@...a.com,
	linux-kernel@...r.kernel.org,
	linux-doc@...r.kernel.org,
	damon@...ts.linux.dev
Subject: Re: [PATCH 0/2] mm/damon: introduce DAMOS filter type for active pages

Hi Nhat,

On Tue, 18 Mar 2025 11:30:27 -0700 Nhat Pham <nphamcs@...il.com> wrote:

> The memory reclaim algorithm categorizes pages into active and inactive
> lists, separately for file and anon pages. The system's performance
> relies heavily on the (relative and absolute) accuracy of this
> categorization.
> 
> This patch series add a new DAMOS filter for pages' activeness, giving
> us visibility into the access frequency of the pages on each list. This
> insight can help us diagnose issues with the active-inactive balancing
> dynamics, and make decisions to optimize reclaim efficiency and memory
> utilization.
> 
> For instance, we might decide to enable DAMON_LRU_SORT, if we find that
> there are pages on the active list that are infrequently accessed, or
> less frequently accessed than pages on the inactive list.

I agree to all the points, and thank you very much for this great patch series.

For other readers' information, DAMOS filters are for visibility of not only
the human users, but also DAMOS itself.  This new filter type will also be very
useful at making DAMOS schemes that respects LRU information (e.g., reclaim
DAMON-found cold pages but only if it is on inactive LRU list).


Thanks,
SJ

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