mm/damon/design.rst

88 and updates the monitoring target address regions so that entire memory
97 address regions is just wasteful.  However, because DAMON can deal with some
98 level of noise using the adaptive regions adjustment mechanism, tracking every
104 distinct regions that cover every mapped area of the address space.  The two
105 gaps between the three regions are the two biggest unmapped areas in the given
115     (small mmap()-ed regions and munmap()-ed regions)
151 ``update interval``, ``minimum number of regions``, and ``maximum number of
152 regions``.
199 controllable by setting the number of regions.  DAMON allows users to set the
200 minimum and the maximum number of regions for the trade-off.
206 Adaptive Regions Adjustment
209 Even somehow the initial monitoring target regions are well constructed to
216 (``nr_accesses``) of adjacent regions.  If the difference is small, and if the
217 sum of the two regions' sizes is smaller than the size of total regions divided
218 by the ``minimum number of regions``, DAMON merges the two regions.  If the
219 resulting number of total regions is still higher than ``maximum number of
220 regions``, it repeats the merging with increasing access frequenceis difference
221 threshold until the upper-limit of the number of regions is met, or the
225 three regions if the total number of regions will not exceed the user-specified
226 maximum number of regions after the split.
263 :ref:`DAMOS tried regions <sysfs_schemes_tried_regions>` and :ref:`tracepoint`,
275     paging out memory regions that are not accessed for more than two minutes
279     using THP for memory regions that are larger than 2 MiB and showing a high
284 workloads or the system using DAMON, finding memory regions of special
286 operation changes for the regions.  The changes could be made by modifying or
301 level.  For such specifications, DAMON starts monitoring, finds regions having
303 to the regions, for every user-specified time interval called
316 The management action that the users desire to apply to the regions of their
319 collecting statistics of the regions.
347  - ``migrate_hot``: Migrate the regions prioritizing warmer regions.
349  - ``migrate_cold``: Migrate the regions prioritizing colder regions.
355 region's characteristics.  Hence, DAMOS resets the age of regions when any such
373 regions that the scheme is having an interest in.
395 can use for applying the action, and/or a maximum bytes of memory regions that
409 cannot be applied to all regions of interest due to the quotas, DAMOS
410 prioritizes regions and applies the action to only regions having high enough
414 rarely accessed (colder) memory regions would be prioritized for page-out
415 scheme action.  In contrast, the colder regions would be deprioritized for huge
420 to calculate the priority using the access pattern properties of the regions.
498 Non-access pattern-based target memory regions filtering.  If users run
514 case of the core layer-handled filters, the memory regions that excluded by the
516 a memory regions is filtered by an operations set layer-handled filter, it is