Lines Matching +full:over +full:- +full:sampling
1 .. SPDX-License-Identifier: GPL-2.0
13 The monitoring-related information including the monitoring request
14 specification and DAMON-based operation schemes are stored in a data structure
19 To know how user-space can do the configurations and start/stop DAMON, refer to
28 - :ref:`Operations Set <damon_operations_set>`: Implements fundamental
30 address-space and available set of software/hardware primitives,
31 - :ref:`Core <damon_core_logic>`: Implements core logics including monitoring
32 overhead/accuracy control and access-aware system operations on top of the
34 - :ref:`Modules <damon_modules>`: Implements kernel modules for various
49 monitoring are address-space dependent.
73 - vaddr: Monitor virtual address spaces of specific processes
74 - fvaddr: Monitor fixed virtual address ranges
75 - paddr: Monitor the physical address space of the system
77 To know how user-space can do the configuration via :ref:`DAMON sysfs interface
84 VMA-based Target Address Range Construction
85 -------------------------------------------
95 Only small parts in the super-huge virtual address space of the processes are
107 heap and the uppermost mmap()-ed region, and the gap between the lowermost
108 mmap()-ed region and the stack in most of the cases. Because these gaps are
110 to make a reasonable trade-off. Below shows this in detail::
114 <uppermost mmap()-ed region>
115 (small mmap()-ed regions and munmap()-ed regions)
116 <lowermost mmap()-ed region>
121 PTE Accessed-bit Based Access Check
122 -----------------------------------
125 Accessed-bit for basic access checks. Only one difference is the way of
130 and clear the bit(s) for next sampling target address and checks whether the
131 bit(s) set again after one sampling period. This could disturb other kernel
147 ----------
150 monitoring attributes, ``sampling interval``, ``aggregation interval``,
154 To know how user-space can set the attributes via :ref:`DAMON sysfs interface
164 ``sampling interval`` and ``aggregation interval``. In detail, DAMON checks
165 access to each page per ``sampling interval`` and aggregates the results. In
169 clears the results. This can be described in below simple pseudo-code::
180 sleep(sampling interval)
188 Region Based Sampling
194 one page in the region is required to be checked. Thus, for each ``sampling
196 ``sampling interval``, checks whether the page is accessed meanwhile, and
200 minimum and the maximum number of regions for the trade-off.
221 threshold until the upper-limit of the number of regions is met, or the
223 divided by ``sampling interval``). Then, after it reports and clears the
225 three regions if the total number of regions will not exceed the user-specified
228 In this way, DAMON provides its best-effort quality and minimal overhead while
229 keeping the bounds users set for their trade-off.
253 be hot-plugged.
257 and applies it to monitoring operations-related data structures such as the
258 abstracted monitoring target memory area only for each of a user-specified time
261 User-space can get the monitoring results via DAMON sysfs interface and/or
270 -----------------
272 One common purpose of data access monitoring is access-aware system efficiency
282 One straightforward approach for such schemes would be profile-guided
299 works, DAMON provides a feature called Data Access Monitoring-based Operation
302 the access pattern of interest, and applies the user-desired operation actions
303 to the regions, for every user-specified time interval called
306 To know how user-space can set ``apply_interval`` via :ref:`DAMON sysfs
333 - ``willneed``: Call ``madvise()`` for the region with ``MADV_WILLNEED``.
335 - ``cold``: Call ``madvise()`` for the region with ``MADV_COLD``.
337 - ``pageout``: Reclaim the region.
339 - ``hugepage``: Call ``madvise()`` for the region with ``MADV_HUGEPAGE``.
341 - ``nohugepage``: Call ``madvise()`` for the region with ``MADV_NOHUGEPAGE``.
343 - ``lru_prio``: Prioritize the region on its LRU lists.
345 - ``lru_deprio``: Deprioritize the region on its LRU lists.
347 - ``migrate_hot``: Migrate the regions prioritizing warmer regions.
349 - ``migrate_cold``: Migrate the regions prioritizing colder regions.
351 - ``stat``: Do nothing but count the statistics.
358 To know how user-space can set the action via :ref:`DAMON sysfs interface
375 To know how user-space can set the access pattern via :ref:`DAMON sysfs
385 DAMOS upper-bound overhead control feature. DAMOS could incur high overhead if
393 To mitigate that situation, DAMOS provides an upper-bound overhead control
396 the action can be applied within a user-specified time duration.
398 To know how user-space can set the basic quotas via :ref:`DAMON sysfs interface
414 rarely accessed (colder) memory regions would be prioritized for page-out
429 To know how user-space can set the prioritization weights via :ref:`DAMON sysfs
436 Aim-oriented Feedback-driven Auto-tuning
439 Automatic feedback-driven quota tuning. Instead of setting the absolute quota
444 is over achieving the goal, it decreases the quota.
447 ``target_value``, and ``current_value``. The auto-tuning mechanism tries to
451 - ``user_input``: User-provided value. Users could use any metric that they
457 - ``some_mem_psi_us``: System-wide ``some`` memory pressure stall information
460 set by users at the initial time. In other words, DAMOS does self-feedback.
462 To know how user-space can set the tuning goal metric, the target value, and/or
488 To know how user-space can set the watermarks via :ref:`DAMON sysfs interface
498 Non-access pattern-based target memory regions filtering. If users run
499 self-written programs or have good profiling tools, they could know something
503 have a list of latency-critical processes.
508 memory, and whether it should exclude the memory of the type (filter-out), or
509 all except the memory of the type (filter-in).
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
521 - anonymous page
522 - Applied to pages that containing data that not stored in files.
523 - Handled by operations set layer. Supported by only ``paddr`` set.
524 - memory cgroup
525 - Applied to pages that belonging to a given cgroup.
526 - Handled by operations set layer. Supported by only ``paddr`` set.
527 - young page
528 - Applied to pages that are accessed after the last access check from the
530 - Handled by operations set layer. Supported by only ``paddr`` set.
531 - address range
532 - Applied to pages that belonging to a given address range.
533 - Handled by the core logic.
534 - DAMON monitoring target
535 - Applied to pages that belonging to a given DAMON monitoring target.
536 - Handled by the core logic.
538 To know how user-space can set the watermarks via :ref:`DAMON sysfs interface
544 ---------------------------------
546 The programming interface for kernel space data access-aware applications.
549 access-aware applications using DAMON's core features. For this, DAMON exposes
564 for general purpose DAMON control and special purpose data access-aware system
566 user space. The user space can build their efficient data access-aware
571 --------------------------------------
578 user-space. Please note that DAMON debugfs interface is currently deprecated.
584 API, and return the results to the user-space.
588 user space tools. One such Python-written user space tool is available at
591 (https://packages.fedoraproject.org/pkgs/python-damo/damo/).
593 Please refer to the ABI :doc:`document </admin-guide/mm/damon/usage>` for
597 Special-Purpose Access-aware Kernel Modules
598 -------------------------------------------
603 in runtime. For each special-purpose system-wide data access-aware system
606 extended for boot-time and even compile time control. Default values of DAMON
614 (:doc:`/admin-guide/mm/damon/reclaim` and
615 :doc:`/admin-guide/mm/damon/lru_sort`).