writing kernel space DAMON application programs for you. You can even extend
DAMON for various address spaces. For detail, please refer to the interface
:doc:`document </mm/damon/api>`.
-- *debugfs interface. (DEPRECATED!)*
- :ref:`This <debugfs_interface>` is almost identical to :ref:`sysfs interface
- <sysfs_interface>`. This is deprecated, so users should move to the
- :ref:`sysfs interface <sysfs_interface>`. If you depend on this and cannot
- move, please report your usecase to damon@lists.linux.dev and
- linux-mm@kvack.org.
.. _sysfs_interface:
of the scheme in the list of the contexts of the context's kdamond, the index
of the scheme (``scheme_idx=X``) in the list of the schemes of the context, in
addition to the output of ``damon_aggregated`` tracepoint.
-
-
-.. _debugfs_interface:
-
-debugfs Interface (DEPRECATED!)
-===============================
-
-.. note::
-
- THIS IS DEPRECATED!
-
- DAMON debugfs interface is deprecated, so users should move to the
- :ref:`sysfs interface <sysfs_interface>`. If you depend on this and cannot
- move, please report your usecase to damon@lists.linux.dev and
- linux-mm@kvack.org.
-
-DAMON exports nine files, ``DEPRECATED``, ``attrs``, ``target_ids``,
-``init_regions``, ``schemes``, ``monitor_on_DEPRECATED``, ``kdamond_pid``,
-``mk_contexts`` and ``rm_contexts`` under its debugfs directory,
-``<debugfs>/damon/``.
-
-
-``DEPRECATED`` is a read-only file for the DAMON debugfs interface deprecation
-notice. Reading it returns the deprecation notice, as below::
-
- # cat DEPRECATED
- DAMON debugfs interface is deprecated, so users should move to DAMON_SYSFS. If you cannot, please report your usecase to damon@lists.linux.dev and linux-mm@kvack.org.
-
-
-Attributes
-----------
-
-Users can get and set the ``sampling interval``, ``aggregation interval``,
-``update interval``, and min/max number of monitoring target regions by
-reading from and writing to the ``attrs`` file. To know about the monitoring
-attributes in detail, please refer to the :doc:`/mm/damon/design`. For
-example, below commands set those values to 5 ms, 100 ms, 1,000 ms, 10 and
-1000, and then check it again::
-
- # cd <debugfs>/damon
- # echo 5000 100000 1000000 10 1000 > attrs
- # cat attrs
- 5000 100000 1000000 10 1000
-
-
-Target IDs
-----------
-
-Some types of address spaces supports multiple monitoring target. For example,
-the virtual memory address spaces monitoring can have multiple processes as the
-monitoring targets. Users can set the targets by writing relevant id values of
-the targets to, and get the ids of the current targets by reading from the
-``target_ids`` file. In case of the virtual address spaces monitoring, the
-values should be pids of the monitoring target processes. For example, below
-commands set processes having pids 42 and 4242 as the monitoring targets and
-check it again::
-
- # cd <debugfs>/damon
- # echo 42 4242 > target_ids
- # cat target_ids
- 42 4242
-
-Users can also monitor the physical memory address space of the system by
-writing a special keyword, "``paddr\n``" to the file. Because physical address
-space monitoring doesn't support multiple targets, reading the file will show a
-fake value, ``42``, as below::
-
- # cd <debugfs>/damon
- # echo paddr > target_ids
- # cat target_ids
- 42
-
-Note that setting the target ids doesn't start the monitoring.
-
-
-Initial Monitoring Target Regions
----------------------------------
-
-In case of the virtual address space 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 contrast, DAMON do not automatically sets and updates the monitoring target
-regions in case of physical memory monitoring. Therefore, users should set the
-monitoring target regions by themselves.
-
-In such cases, users can explicitly set the initial monitoring target regions
-as they want, by writing proper values to the ``init_regions`` file. The input
-should be a sequence of three integers separated by white spaces that represent
-one region in below form.::
-
- <target idx> <start address> <end address>
-
-The ``target idx`` should be the index of the target in ``target_ids`` file,
-starting from ``0``, 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 pid 42, which is the
-first one (index ``0``) in ``target_ids``, and another couple of address
-ranges, ``20-40`` and ``50-100`` as that of pid 4242, which is the second one
-(index ``1``) in ``target_ids``.::
-
- # cd <debugfs>/damon
- # cat target_ids
- 42 4242
- # echo "0 1 100 \
- 0 100 200 \
- 1 20 40 \
- 1 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 ``update interval``. Therefore, users should set the
-``update interval`` large enough in this case, if they don't want the
-update.
-
-
-Schemes
--------
-
-Users can get and set the DAMON-based operation :ref:`schemes
-<damon_design_damos>` by reading from and writing to ``schemes`` debugfs file.
-Reading the file also shows the statistics of each scheme. To the file, each
-of the schemes should be represented in each line in below form::
-
- <target access pattern> <action> <quota> <watermarks>
-
-You can disable schemes by simply writing an empty string to the file.
-
-Target Access Pattern
-~~~~~~~~~~~~~~~~~~~~~
-
-The target access :ref:`pattern <damon_design_damos_access_pattern>` of the
-scheme. The ``<target access pattern>`` is constructed with three ranges in
-below form::
-
- min-size max-size min-acc max-acc min-age max-age
-
-Specifically, bytes for the size of regions (``min-size`` and ``max-size``),
-number of monitored accesses per aggregate interval for access frequency
-(``min-acc`` and ``max-acc``), number of aggregate intervals for the age of
-regions (``min-age`` and ``max-age``) are specified. Note that the ranges are
-closed interval.
-
-Action
-~~~~~~
-
-The ``<action>`` is a predefined integer for memory management :ref:`actions
-<damon_design_damos_action>`. The mapping between the ``<action>`` values and
-the memory management actions is as below. For the detailed meaning of the
-action and DAMON operations set supporting each action, please refer to the
-list on :ref:`design doc <damon_design_damos_action>`.
-
- - 0: ``willneed``
- - 1: ``cold``
- - 2: ``pageout``
- - 3: ``hugepage``
- - 4: ``nohugepage``
- - 5: ``stat``
-
-Quota
-~~~~~
-
-Users can set the :ref:`quotas <damon_design_damos_quotas>` of the given scheme
-via the ``<quota>`` in below form::
-
- <ms> <sz> <reset interval> <priority weights>
-
-This makes DAMON to try to use only up to ``<ms>`` milliseconds for applying
-the action to memory regions of the ``target access pattern`` within the
-``<reset interval>`` milliseconds, and to apply the action to only up to
-``<sz>`` bytes of memory regions within the ``<reset interval>``. Setting both
-``<ms>`` and ``<sz>`` zero disables the quota limits.
-
-For the :ref:`prioritization <damon_design_damos_quotas_prioritization>`, users
-can set the weights for the three properties in ``<priority weights>`` in below
-form::
-
- <size weight> <access frequency weight> <age weight>
-
-Watermarks
-~~~~~~~~~~
-
-Users can specify :ref:`watermarks <damon_design_damos_watermarks>` of the
-given scheme via ``<watermarks>`` in below form::
-
- <metric> <check interval> <high mark> <middle mark> <low mark>
-
-``<metric>`` is a predefined integer for the metric to be checked. The
-supported numbers and their meanings are as below.
-
- - 0: Ignore the watermarks
- - 1: System's free memory rate (per thousand)
-
-The value of the metric is checked every ``<check interval>`` microseconds.
-
-If the value is higher than ``<high mark>`` or lower than ``<low mark>``, the
-scheme is deactivated. If the value is lower than ``<mid mark>``, the scheme
-is activated.
-
-.. _damos_stats:
-
-Statistics
-~~~~~~~~~~
-
-It also counts the total number and bytes of regions that each scheme is tried
-to be applied, the two numbers for the regions that each scheme is successfully
-applied, and the total number of the quota limit exceeds. This statistics can
-be used for online analysis or tuning of the schemes.
-
-The statistics can be shown by reading the ``schemes`` file. Reading the file
-will show each scheme you entered in each line, and the five numbers for the
-statistics will be added at the end of each line.
-
-Example
-~~~~~~~
-
-Below commands applies a scheme saying "If a memory region of size in [4KiB,
-8KiB] is showing accesses per aggregate interval in [0, 5] for aggregate
-interval in [10, 20], page out the region. For the paging out, use only up to
-10ms per second, and also don't page out more than 1GiB per second. Under the
-limitation, page out memory regions having longer age first. Also, check the
-free memory rate of the system every 5 seconds, start the monitoring and paging
-out when the free memory rate becomes lower than 50%, but stop it if the free
-memory rate becomes larger than 60%, or lower than 30%".::
-
- # cd <debugfs>/damon
- # scheme="4096 8192 0 5 10 20 2" # target access pattern and action
- # scheme+=" 10 $((1024*1024*1024)) 1000" # quotas
- # scheme+=" 0 0 100" # prioritization weights
- # scheme+=" 1 5000000 600 500 300" # watermarks
- # echo "$scheme" > schemes
-
-
-Turning On/Off
---------------
-
-Setting the files as described above doesn't incur effect unless you explicitly
-start the monitoring. You can start, stop, and check the current status of the
-monitoring by writing to and reading from the ``monitor_on_DEPRECATED`` file.
-Writing ``on`` to the file starts the monitoring of the targets with the
-attributes. Writing ``off`` to the file stops those. DAMON also stops if
-every target process is terminated. Below example commands turn on, off, and
-check the status of DAMON::
-
- # cd <debugfs>/damon
- # echo on > monitor_on_DEPRECATED
- # echo off > monitor_on_DEPRECATED
- # cat monitor_on_DEPRECATED
- off
-
-Please note that you cannot write to the above-mentioned debugfs files while
-the monitoring is turned on. If you write to the files while DAMON is running,
-an error code such as ``-EBUSY`` will be returned.
-
-
-Monitoring Thread PID
----------------------
-
-DAMON does requested monitoring with a kernel thread called ``kdamond``. You
-can get the pid of the thread by reading the ``kdamond_pid`` file. When the
-monitoring is turned off, reading the file returns ``none``. ::
-
- # cd <debugfs>/damon
- # cat monitor_on_DEPRECATED
- off
- # cat kdamond_pid
- none
- # echo on > monitor_on_DEPRECATED
- # cat kdamond_pid
- 18594
-
-
-Using Multiple Monitoring Threads
----------------------------------
-
-One ``kdamond`` thread is created for each monitoring context. You can create
-and remove monitoring contexts for multiple ``kdamond`` required use case using
-the ``mk_contexts`` and ``rm_contexts`` files.
-
-Writing the name of the new context to the ``mk_contexts`` file creates a
-directory of the name on the DAMON debugfs directory. The directory will have
-DAMON debugfs files for the context. ::
-
- # cd <debugfs>/damon
- # ls foo
- # ls: cannot access 'foo': No such file or directory
- # echo foo > mk_contexts
- # ls foo
- # attrs init_regions kdamond_pid schemes target_ids
-
-If the context is not needed anymore, you can remove it and the corresponding
-directory by putting the name of the context to the ``rm_contexts`` file. ::
-
- # echo foo > rm_contexts
- # ls foo
- # ls: cannot access 'foo': No such file or directory
-
-Note that ``mk_contexts``, ``rm_contexts``, and ``monitor_on_DEPRECATED`` files
-are in the root directory only.
projects / users / jedix / linux-maple.git / commitdiff