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Docs/admin-guide/mm/damon: document 'init_regions' feature

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This adds description of the 'init_regions' feature in the DAMON usage
document.

Link: https://lkml.kernel.org/r/20211012205711.29216-4-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Amit Shah <amit@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rienjes <rientjes@google.com>
Cc: David Woodhouse <dwmw@amazon.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Leonard Foerster <foersleo@amazon.de>
Cc: Marco Elver <elver@google.com>
Cc: Markus Boehme <markubo@amazon.de>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
SeongJae Park 2021-11-05 13:46:49 -07:00 committed by Linus Torvalds
parent 1c2e11bfa6
commit c2fe4987ed
1 changed files with 39 additions and 2 deletions
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41
Documentation/admin-guide/mm/damon/usage.rst
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@ -34,8 +34,9 @@ the reason, this document describes only the debugfs interface
debugfs Interface
=================
DAMON exports four files, ``attrs``, ``target_ids``, ``schemes`` and
``monitor_on`` under its debugfs directory, ``<debugfs>/damon/``.
DAMON exports five files, ``attrs``, ``target_ids``, ``init_regions``,
``schemes`` and ``monitor_on`` under its debugfs directory,
``<debugfs>/damon/``.
Attributes
@ -74,6 +75,42 @@ check it again::
Note that setting the target ids doesn't start the monitoring.
Initial Monitoring Target Regions
---------------------------------
In case of the debugfs based monitoring, DAMON automatically sets and updates
the monitoring target regions so that entire memory mappings of target
processes can be covered. However, users can want to limit the monitoring
region to specific address ranges, such as the heap, the stack, or specific
file-mapped area. Or, some users can know the initial access pattern of their
workloads and therefore want to set optimal initial regions for the 'adaptive
regions adjustment'.
In such cases, users can explicitly set the initial monitoring target regions
as they want, by writing proper values to the ``init_regions`` file. Each line
of the input should represent one region in below form.::
<target id> <start address> <end address>
The ``target id`` should already in ``target_ids`` file, and the regions should
be passed in address order. For example, below commands will set a couple of
address ranges, ``1-100`` and ``100-200`` as the initial monitoring target
region of process 42, and another couple of address ranges, ``20-40`` and
``50-100`` as that of process 4242.::
# cd <debugfs>/damon
# echo "42 1 100
42 100 200
4242 20 40
4242 50 100" > init_regions
Note that this sets the initial monitoring target regions only. In case of
virtual memory monitoring, DAMON will automatically updates the boundary of the
regions after one ``regions update interval``. Therefore, users should set the
``regions update interval`` large enough in this case, if they don't want the
update.
Schemes
-------