user/sven/linux.git/include/linux/damon.h, branch v5.18.3

mm/damon/core: add number of each enum type values

2022-03-22T22:57:13Z

This commit declares the number of legal values for each DAMON enum types to make traversals of such DAMON enum types easy and safe. Link: https://lkml.kernel.org/r/20220228081314.5770-3-sj@kernel.org Signed-off-by: SeongJae Park Cc: David Rientjes Cc: Greg Kroah-Hartman Cc: Jonathan Corbet Cc: Shuah Khan Cc: Xin Hao Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/damon/core: allow non-exclusive DAMON start/stop

2022-03-22T22:57:13Z

Patch series "Introduce DAMON sysfs interface", v3. Introduction ============ DAMON's debugfs-based user interface (DAMON_DBGFS) served very well, so far. However, it unnecessarily depends on debugfs, while DAMON is not aimed to be used for only debugging. Also, the interface receives multiple values via one file. For example, schemes file receives 18 values. As a result, it is inefficient, hard to be used, and difficult to be extended. Especially, keeping backward compatibility of user space tools is getting only challenging. It would be better to implement another reliable and flexible interface and deprecate DAMON_DBGFS in long term. For the reason, this patchset introduces a sysfs-based new user interface of DAMON. The idea of the new interface is, using directory hierarchies and having one dedicated file for each value. For a short example, users can do the virtual address monitoring via the interface as below: # cd /sys/kernel/mm/damon/admin/ # echo 1 > kdamonds/nr_kdamonds # echo 1 > kdamonds/0/contexts/nr_contexts # echo vaddr > kdamonds/0/contexts/0/operations # echo 1 > kdamonds/0/contexts/0/targets/nr_targets # echo $(pidof ) > kdamonds/0/contexts/0/targets/0/pid_target # echo on > kdamonds/0/state A brief representation of the files hierarchy of DAMON sysfs interface is as below. Childs are represented with indentation, directories are having '/' suffix, and files in each directory are separated by comma. /sys/kernel/mm/damon/admin │ kdamonds/nr_kdamonds │ │ 0/state,pid │ │ │ contexts/nr_contexts │ │ │ │ 0/operations │ │ │ │ │ monitoring_attrs/ │ │ │ │ │ │ intervals/sample_us,aggr_us,update_us │ │ │ │ │ │ nr_regions/min,max │ │ │ │ │ targets/nr_targets │ │ │ │ │ │ 0/pid_target │ │ │ │ │ │ │ regions/nr_regions │ │ │ │ │ │ │ │ 0/start,end │ │ │ │ │ │ │ │ ... │ │ │ │ │ │ ... │ │ │ │ │ schemes/nr_schemes │ │ │ │ │ │ 0/action │ │ │ │ │ │ │ access_pattern/ │ │ │ │ │ │ │ │ sz/min,max │ │ │ │ │ │ │ │ nr_accesses/min,max │ │ │ │ │ │ │ │ age/min,max │ │ │ │ │ │ │ quotas/ms,bytes,reset_interval_ms │ │ │ │ │ │ │ │ weights/sz_permil,nr_accesses_permil,age_permil │ │ │ │ │ │ │ watermarks/metric,interval_us,high,mid,low │ │ │ │ │ │ │ stats/nr_tried,sz_tried,nr_applied,sz_applied,qt_exceeds │ │ │ │ │ │ ... │ │ │ │ ... │ │ ... Detailed usage of the files will be described in the final Documentation patch of this patchset. Main Difference Between DAMON_DBGFS and DAMON_SYSFS --------------------------------------------------- At the moment, DAMON_DBGFS and DAMON_SYSFS provides same features. One important difference between them is their exclusiveness. DAMON_DBGFS works in an exclusive manner, so that no DAMON worker thread (kdamond) in the system can run concurrently and interfere somehow. For the reason, DAMON_DBGFS asks users to construct all monitoring contexts and start them at once. It's not a big problem but makes the operation a little bit complex and unflexible. For more flexible usage, DAMON_SYSFS moves the responsibility of preventing any possible interference to the admins and work in a non-exclusive manner. That is, users can configure and start contexts one by one. Note that DAMON respects both exclusive groups and non-exclusive groups of contexts, in a manner similar to that of reader-writer locks. That is, if any exclusive monitoring contexts (e.g., contexts that started via DAMON_DBGFS) are running, DAMON_SYSFS does not start new contexts, and vice versa. Future Plan of DAMON_DBGFS Deprecation ====================================== Once this patchset is merged, DAMON_DBGFS development will be frozen. That is, we will maintain it to work as is now so that no users will be break. But, it will not be extended to provide any new feature of DAMON. The support will be continued only until next LTS release. After that, we will drop DAMON_DBGFS. User-space Tooling Compatibility -------------------------------- As DAMON_SYSFS provides all features of DAMON_DBGFS, all user space tooling can move to DAMON_SYSFS. As we will continue supporting DAMON_DBGFS until next LTS kernel release, user space tools would have enough time to move to DAMON_SYSFS. The official user space tool, damo[1], is already supporting both DAMON_SYSFS and DAMON_DBGFS. Both correctness tests[2] and performance tests[3] of DAMON using DAMON_SYSFS also passed. [1] https://github.com/awslabs/damo [2] https://github.com/awslabs/damon-tests/tree/master/corr [3] https://github.com/awslabs/damon-tests/tree/master/perf Sequence of Patches =================== First two patches (patches 1-2) make core changes for DAMON_SYSFS. The first one (patch 1) allows non-exclusive DAMON contexts so that DAMON_SYSFS can work in non-exclusive mode, while the second one (patch 2) adds size of DAMON enum types so that DAMON API users can safely iterate the enums. Third patch (patch 3) implements basic sysfs stub for virtual address spaces monitoring. Note that this implements only sysfs files and DAMON is not linked. Fourth patch (patch 4) links the DAMON_SYSFS to DAMON so that users can control DAMON using the sysfs files. Following six patches (patches 5-10) implements other DAMON features that DAMON_DBGFS supports one by one (physical address space monitoring, DAMON-based operation schemes, schemes quotas, schemes prioritization weights, schemes watermarks, and schemes stats). Following patch (patch 11) adds a simple selftest for DAMON_SYSFS, and the final one (patch 12) documents DAMON_SYSFS. This patch (of 13): To avoid interference between DAMON contexts monitoring overlapping memory regions, damon_start() works in an exclusive manner. That is, damon_start() does nothing bug fails if any context that started by another instance of the function is still running. This makes its usage a little bit restrictive. However, admins could aware each DAMON usage and address such interferences on their own in some cases. This commit hence implements non-exclusive mode of the function and allows the callers to select the mode. Note that the exclusive groups and non-exclusive groups of contexts will respect each other in a manner similar to that of reader-writer locks. Therefore, this commit will not cause any behavioral change to the exclusive groups. Link: https://lkml.kernel.org/r/20220228081314.5770-1-sj@kernel.org Link: https://lkml.kernel.org/r/20220228081314.5770-2-sj@kernel.org Signed-off-by: SeongJae Park Cc: Jonathan Corbet Cc: Shuah Khan Cc: David Rientjes Cc: Xin Hao Cc: Greg Kroah-Hartman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/damon/paddr,vaddr: remove damon_{p,v}a_{target_valid,set_operations}()

2022-03-22T22:57:12Z

Because DAMON debugfs interface and DAMON-based proactive reclaim are now using monitoring operations via registration mechanism, damon_{p,v}a_{target_valid,set_operations}() functions have no user. This commit clean them up. Link: https://lkml.kernel.org/r/20220215184603.1479-9-sj@kernel.org Signed-off-by: SeongJae Park Cc: David Rientjes Cc: Xin Hao Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/damon: let monitoring operations can be registered and selected

2022-03-22T22:57:12Z

In-kernel DAMON user code like DAMON debugfs interface should set 'struct damon_operations' of its 'struct damon_ctx' on its own. Therefore, the client code should depend on all supporting monitoring operations implementations that it could use. For example, DAMON debugfs interface depends on both vaddr and paddr, while some of the users are not always interested in both. To minimize such unnecessary dependencies, this commit makes the monitoring operations can be registered by implementing code and then dynamically selected by the user code without build-time dependency. Link: https://lkml.kernel.org/r/20220215184603.1479-3-sj@kernel.org Signed-off-by: SeongJae Park Cc: David Rientjes Cc: Xin Hao Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/damon: rename damon_primitives to damon_operations

2022-03-22T22:57:12Z

Patch series "Allow DAMON user code independent of monitoring primitives". In-kernel DAMON user code is required to configure the monitoring context (struct damon_ctx) with proper monitoring primitives (struct damon_primitive). This makes the user code dependent to all supporting monitoring primitives. For example, DAMON debugfs interface depends on both DAMON_VADDR and DAMON_PADDR, though some users have interest in only one use case. As more monitoring primitives are introduced, the problem will be bigger. To minimize such unnecessary dependency, this patchset makes monitoring primitives can be registered by the implemnting code and later dynamically searched and selected by the user code. In addition to that, this patchset renames monitoring primitives to monitoring operations, which is more easy to intuitively understand what it means and how it would be structed. This patch (of 8): DAMON has a set of callback functions called monitoring primitives and let it can be configured with various implementations for easy extension for different address spaces and usages. However, the word 'primitive' is not so explicit. Meanwhile, many other structs resembles similar purpose calls themselves 'operations'. To make the code easier to be understood, this commit renames 'damon_primitives' to 'damon_operations' before it is too late to rename. Link: https://lkml.kernel.org/r/20220215184603.1479-1-sj@kernel.org Link: https://lkml.kernel.org/r/20220215184603.1479-2-sj@kernel.org Signed-off-by: SeongJae Park Cc: Xin Hao Cc: David Rientjes Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/damon: remove the target id concept

2022-03-22T22:57:12Z

DAMON asks each monitoring target ('struct damon_target') to have one 'unsigned long' integer called 'id', which should be unique among the targets of same monitoring context. Meaning of it is, however, totally up to the monitoring primitives that registered to the monitoring context. For example, the virtual address spaces monitoring primitives treats the id as a 'struct pid' pointer. This makes the code flexible, but ugly, not well-documented, and type-unsafe[1]. Also, identification of each target can be done via its index. For the reason, this commit removes the concept and uses clear type definition. For now, only 'struct pid' pointer is used for the virtual address spaces monitoring. If DAMON is extended in future so that we need to put another identifier field in the struct, we will use a union for such primitives-dependent fields and document which primitives are using which type. [1] https://lore.kernel.org/linux-mm/20211013154535.4aaeaaf9d0182922e405dd1e@linux-foundation.org/ Link: https://lkml.kernel.org/r/20211230100723.2238-5-sj@kernel.org Signed-off-by: SeongJae Park Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/damon/core: move damon_set_targets() into dbgfs

2022-03-22T22:57:12Z

damon_set_targets() function is defined in the core for general use cases, but called from only dbgfs. Also, because the function is for general use cases, dbgfs does additional handling of pid type target id case. To make the situation simpler, this commit moves the function into dbgfs and makes it to do the pid type case handling on its own. Link: https://lkml.kernel.org/r/20211230100723.2238-4-sj@kernel.org Signed-off-by: SeongJae Park Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/damon: move the implementation of damon_insert_region to damon.h

2022-01-15T14:30:33Z

Usually, inline function is declared static since it should sit between storage and type. And implement it in a header file if used by multiple files. And this change also fixes compile issue when backport damon to 5.10. mm/damon/vaddr.c: In function `damon_va_evenly_split_region': ./include/linux/damon.h:425:13: error: inlining failed in call to `always_inline' `damon_insert_region': function body not available 425 | inline void damon_insert_region(struct damon_region *r, | ^~~~~~~~~~~~~~~~~~~ mm/damon/vaddr.c:86:3: note: called from here 86 | damon_insert_region(n, r, next, t); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Link: https://lkml.kernel.org/r/20211223085703.6142-1-guoqing.jiang@linux.dev Signed-off-by: Guoqing Jiang Reviewed-by: SeongJae Park Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/damon/schemes: account how many times quota limit has exceeded

2022-01-15T14:30:33Z

If the time/space quotas of a given DAMON-based operation scheme is too small, the scheme could show unexpectedly slow progress. However, there is no good way to notice the case in runtime. This commit extends the DAMOS stat to provide how many times the quota limits exceeded so that the users can easily notice the case and tune the scheme. Link: https://lkml.kernel.org/r/20211210150016.35349-3-sj@kernel.org Signed-off-by: SeongJae Park Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/damon/schemes: account scheme actions that successfully applied

2022-01-15T14:30:32Z

Patch series "mm/damon/schemes: Extend stats for better online analysis and tuning". To help online access pattern analysis and tuning of DAMON-based Operation Schemes (DAMOS), DAMOS provides simple statistics for each scheme. Introduction of DAMOS time/space quota further made the tuning easier by making the risk management easier. However, that also made understanding of the working schemes a little bit more difficult. For an example, progress of a given scheme can now be throttled by not only the aggressiveness of the target access pattern, but also the time/space quotas. So, when a scheme is showing unexpectedly slow progress, it's difficult to know by what the progress of the scheme is throttled, with currently provided statistics. This patchset extends the statistics to contain some metrics that can be helpful for such online schemes analysis and tuning (patches 1-2), exports those to users (patches 3 and 5), and add documents (patches 4 and 6). This patch (of 6): DAMON-based operation schemes (DAMOS) stats provide only the number and the amount of regions that the action of the scheme has tried to be applied. Because the action could be failed for some reasons, the currently provided information is sometimes not useful or convenient enough for schemes profiling and tuning. To improve this situation, this commit extends the DAMOS stats to provide the number and the amount of regions that the action has successfully applied. Link: https://lkml.kernel.org/r/20211210150016.35349-1-sj@kernel.org Link: https://lkml.kernel.org/r/20211210150016.35349-2-sj@kernel.org Signed-off-by: SeongJae Park Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds