Commit b3b95a35 authored by SeongJae Park's avatar SeongJae Park Committed by Andrew Morton
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Docs/mm/damon/design: document node_mem_{used,free}_bp 

Add description of DAMOS quota goal metrics for NUMA node utilization on
the DAMON deesign document.

Link: https://lkml.kernel.org/r/20250420194030.75838-5-sj@kernel.org


Signed-off-by: default avatarSeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Yunjeong Mun <yunjeong.mun@sk.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 85fcf0ff

Documentation/mm/damon/design.rst

+9 −4
Original line number Diff line number Diff line
@@ -550,10 +550,10 @@ aggressiveness (the quota) of the corresponding scheme. For example, if DAMOS 
is under achieving the goal, DAMOS automatically increases the quota.  If DAMOS

is over achieving the goal, it decreases the quota.



The goal can be specified with three parameters, namely ``target_metric``,

``target_value``, and ``current_value``.  The auto-tuning mechanism tries to

make ``current_value`` of ``target_metric`` be same to ``target_value``.

Currently, two ``target_metric`` are provided.

The goal can be specified with four parameters, namely ``target_metric``,

``target_value``, ``current_value`` and ``nid``.  The auto-tuning mechanism

tries to make ``current_value`` of ``target_metric`` be same to

``target_value``.



- ``user_input``: User-provided value.  Users could use any metric that they

  has interest in for the value.  Use space main workload's latency or
@@ -565,6 +565,11 @@ Currently, two ``target_metric`` are provided. 
  in microseconds that measured from last quota reset to next quota reset.

  DAMOS does the measurement on its own, so only ``target_value`` need to be

  set by users at the initial time.  In other words, DAMOS does self-feedback.

- ``node_mem_used_bp``: Specific NUMA node's used memory ratio in bp (1/10,000).

- ``node_mem_free_bp``: Specific NUMA node's free memory ratio in bp (1/10,000).



``nid`` is optionally required for only ``node_mem_used_bp`` and

``node_mem_free_bp`` to point the specific NUMA node.



To know how user-space can set the tuning goal metric, the target value, and/or

the current value via :ref:`DAMON sysfs interface <sysfs_interface>`, refer to