+ docs-mm-damon-design-document-age-of-region.patch added to mm-unstable branch

+ docs-mm-damon-design-document-age-of-region.patch added to mm-unstable branch

[Andrew Morton]

The patch titled
     Subject: Docs/mm/damon/design: document 'age' of region
has been added to the -mm mm-unstable branch.  Its filename is
     docs-mm-damon-design-document-age-of-region.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/docs-mm-damon-design-document-age-of-region.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: SeongJae Park <sj@kernel.org>
Subject: Docs/mm/damon/design: document 'age' of region
Date: Fri, 16 Jun 2023 19:17:36 +0000

Patch series "Docs/{mm,admin-guide}damon: update design and usage docs".

Update DAMON design and usage documents for outdated and unnecessarily
duplicated parts.


This patch (of 7):

The 'age' of each region in DAMON monitoring results is an important
concept for both monitoring part and DAMOS.  And DAMOS section of the
design document is mentioning it.  However, the age itself is not
explained in the document.  Add a section for that.

Link: https://lkml.kernel.org/r/20230616191742.87531-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20230616191742.87531-2-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 Documentation/mm/damon/design.rst |   14 ++++++++++++++
 1 file changed, 14 insertions(+)

--- a/Documentation/mm/damon/design.rst~docs-mm-damon-design-document-age-of-region
+++ a/Documentation/mm/damon/design.rst
@@ -190,6 +190,20 @@ In this way, DAMON provides its best-eff
 keeping the bounds users set for their trade-off.
 
 
+Age Tracking
+~~~~~~~~~~~~
+
+By analyzing the monitoring results, users can also find how long the current
+access pattern of a region has maintained.  That could be used for good
+understanding of the access pattern.  For example, page placement algorithm
+utilizing both the frequency and the recency could be implemented using that.
+To make such access pattern maintained period analysis easier, DAMON maintains
+yet another counter called ``age`` in each region.  For each ``aggregation
+interval``, DAMON checks if the region's size and access frequency
+(``nr_accesses``) has significantly changed.  If so, the counter is reset to
+zero.  Otherwise, the counter is increased.
+
+
 Dynamic Target Space Updates Handling
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
_

Patches currently in -mm which might be from sj@kernel.org are

mm-damon-core-test-add-a-test-for-damon_set_attrs.patch
docs-mm-damon-design-document-age-of-region.patch
docs-admin-guide-mm-damon-start-update-damos-example-command.patch
docs-admin-guide-mm-damon-usage-fix-typos-in-references-and-commas.patch
docs-admin-guide-mm-damon-usage-remove-unnecessary-sentences-about-supported-address-spaces.patch
docs-admin-guide-mm-damon-usage-link-design-document-for-damos.patch
docs-admin-guide-mm-damon-usage-clarify-quotas-and-watermarks-sysfs-interface.patch
docs-admin-guide-mm-damon-usage-update-the-ways-for-getting-monitoring-results.patch