mm/damon/design.rst

29   and access-aware system operations on top of the operations set layer, and
37 For data access monitoring and additional low level work, DAMON needs a set of
52 Also, if some architectures or devices supporting special optimized access
72 2. Access check of specific address range in the target space.
111 PTE Accessed-bit Based Access Check
115 Accessed-bit for basic access checks.  Only one difference is the way of
142 Access Frequency Monitoring
146 duration.  The resolution of the access frequency is controlled by setting
148 access to each page per ``sampling interval`` and aggregates the results.  In
175 that assumed to have the same access frequencies into a region.  As long as the
176 assumption (pages in a region have the same access frequencies) is kept, only
180 increases the access frequency counter of the region if so.  The counter is
193 fulfill the assumption (pages in same region have similar access frequencies),
194 the data access pattern can be dynamically changed.  This will result in low
196 adaptively merges and splits each region based on their access frequency.
198 For each ``aggregation interval``, it compares the access frequencies of
200 after it reports and clears the aggregated access frequency of each region, it
214 access pattern of a region has maintained.  That could be used for good
215 understanding of the access pattern.  For example, page placement algorithm
217 To make such access pattern maintained period analysis easier, DAMON maintains
219 interval``, DAMON checks if the region's size and access frequency
243 One common purpose of data access monitoring is access-aware system efficiency
251     access frequency for more than one minute.
254 optimizations.  That is, getting data access monitoring results of the
270 works, DAMON provides a feature called Data Access Monitoring-based Operation
273 the access pattern of interest, and applies the user-desired operation actions
304 Target Access Pattern
307 The access pattern of the schemes' interest.  The patterns are constructed with
309 the access frequency, and the age.  Users can describe their access pattern of
321 the target access pattern is not properly tuned.  For example, if a huge memory
322 region having the access pattern of interest is found, applying the scheme's
324 resources.  Preventing such issues by tuning the access pattern could be
325 challenging, especially if the access patterns of the workloads are highly
351 to calculate the priority using the access pattern properties of the regions.
354 (``age``) more than the access frequency (``nr_accesses``).  DAMOS allows users
355 to specify the weight of each access pattern property and passes the
401 Non-access pattern-based target memory regions filtering.  If users run
403 more than the kernel, such as future access patterns or some special
437 The programming interface for kernel space data access-aware applications.
440 access-aware applications using DAMON's core features.  For this, DAMON exposes
453 for general purpose DAMON control and special purpose data access-aware system
455 user space.  The user space can build their efficient data access-aware
486 Special-Purpose Access-aware Kernel Modules
492 in runtime.  For each special-purpose system-wide data access-aware system