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authorSeongJae Park <sj@kernel.org>2023-06-16 22:17:36 +0300
committerAndrew Morton <akpm@linux-foundation.org>2023-06-20 02:19:36 +0300
commitb16b54c9db8bb4ed34a489ed56cb33d08a12da1a (patch)
treeec5286212cf57c90651b034b778f3a2edca4fc30 /Documentation/mm/damon
parentc1753fd02a0058ea43cbb31ab26d25be2f6cfe08 (diff)
downloadlinux-b16b54c9db8bb4ed34a489ed56cb33d08a12da1a.tar.xz
Docs/mm/damon/design: document 'age' of region
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 Update DAMON design and usage documents for outdated and unnecessarily duplicated parts.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>
Diffstat (limited to 'Documentation/mm/damon')
-rw-r--r--Documentation/mm/damon/design.rst14
1 files changed, 14 insertions, 0 deletions
diff --git a/Documentation/mm/damon/design.rst b/Documentation/mm/damon/design.rst
index da110e89cab4..a98af99bb705 100644
--- a/Documentation/mm/damon/design.rst
+++ b/Documentation/mm/damon/design.rst
@@ -190,6 +190,20 @@ In this way, DAMON provides its best-effort quality and minimal overhead while
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
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~