From: SeongJae Park <sjpark@xxxxxxxxx> Introduction ============ DAMON is a data access monitoring framework subsystem for the Linux kernel. The core mechanisms of DAMON called 'region based sampling' and 'adaptive regions adjustment' (refer to 'mechanisms.rst' in the 11th patch of this patchset for the detail) make it - accurate (The monitored information is useful for DRAM level memory management. It might not appropriate for Cache-level accuracy, though.), - light-weight (The monitoring overhead is low enough to be applied online while making no impact on the performance of the target workloads.), and - scalable (the upper-bound of the instrumentation overhead is controllable regardless of the size of target workloads.). Using this framework, therefore, the kernel's core memory management mechanisms such as reclamation and THP can be optimized for better memory management. The experimental memory management optimization works that incurring high instrumentation overhead will be able to have another try. In user space, meanwhile, users who have some special workloads will be able to write personalized tools or applications for deeper understanding and specialized optimizations of their systems. Evaluations =========== We evaluated DAMON's overhead, monitoring quality and usefulness using 25 realistic workloads on my QEMU/KVM based virtual machine running a kernel that v13 DAMON patchset is applied. DAMON is lightweight. It increases system memory usage by only -0.39% and consumes less than 1% CPU time in most case. It slows target workloads down by only 0.63%. DAMON is accurate and useful for memory management optimizations. An experimental DAMON-based operation scheme for THP, 'ethp', removes 69.43% of THP memory overheads while preserving 37.11% of THP speedup. Another experimental DAMON-based 'proactive reclamation' implementation, 'prcl', reduces 89.30% of residential sets and 22.40% of system memory footprint while incurring only 1.98% runtime overhead in the best case (parsec3/freqmine). NOTE that the experimentail THP optimization and proactive reclamation are not for production, just only for proof of concepts. Please refer to the official document[1] or "Documentation/admin-guide/mm: Add a document for DAMON" patch in this patchset for detailed evaluation setup and results. [1] https://damonitor.github.io/doc/html/latest-damon More Information ================ We prepared a showcase web site[1] that you can get more information. There are - the official documentations[2], - the heatmap format dynamic access pattern of various realistic workloads for heap area[3], mmap()-ed area[4], and stack[5] area, - the dynamic working set size distribution[6] and chronological working set size changes[7], and - the latest performance test results[8]. [1] https://damonitor.github.io/_index [2] https://damonitor.github.io/doc/html/latest-damon [3] https://damonitor.github.io/test/result/visual/latest/heatmap.0.html [4] https://damonitor.github.io/test/result/visual/latest/heatmap.1.html [5] https://damonitor.github.io/test/result/visual/latest/heatmap.2.html [6] https://damonitor.github.io/test/result/visual/latest/wss_sz.html [7] https://damonitor.github.io/test/result/visual/latest/wss_time.html [8] https://damonitor.github.io/test/result/perf/latest/html/index.html Baseline and Complete Git Trees =============================== The patches are based on the v5.7. You can also clone the complete git tree: $ git clone git://github.com/sjp38/linux -b damon/patches/v15 The web is also available: https://github.com/sjp38/linux/releases/tag/damon/patches/v15 There are a couple of trees for entire DAMON patchset series. It includes future features. The first one[1] contains the changes for latest release, while the other one[2] contains the changes for next release. [1] https://github.com/sjp38/linux/tree/damon/master [2] https://github.com/sjp38/linux/tree/damon/next Sequence Of Patches =================== The 1st patch exports 'lookup_page_ext()' to GPL modules so that it can be used by DAMON even though it is built as a loadable module. Next four patches implement the core of DAMON and it's programming interface. The 2nd patch introduces DAMON module, it's data structures, and data structure related common functions. Following three patches (3rd to 5th) implements the core mechanisms of DAMON, namely regions based sampling (patch 3), adaptive regions adjustment (patch 4), and dynamic memory mapping chage adoption (patch 5). Following four patches are for low level users of DAMON. The 6th patch implements callbacks for each of monitoring steps so that users can do whatever they want with the access patterns. The 7th one implements recording of access patterns in DAMON for better convenience and efficiency. Each of next two patches (8th and 9th) respectively adds a debugfs interface for privileged people and/or programs in user space, and a tracepoint for other tracepoints supporting tracers such as perf. Two patches for high level users of DAMON follows. To provide a minimal reference to the debugfs interface and for high level use/tests of the DAMON, the next patch (10th) implements an user space tool. The 11th patch adds a document for administrators of DAMON. Next two patches are for tests. The 12th patch provides unit tests (based on the kunit) while the 13th patch adds user space tests (based on the kselftest). Finally, the last patch (14th) updates the MAINTAINERS file. Patch History ============= Changes from v14 (https://lore.kernel.org/linux-mm/20200602130125.20467-1-sjpark@xxxxxxxxxx/) - Directly pass region and task to tracepoint (Steven Rostedt) - Refine comments for better read - Add more 'Reviewed-by's (Leonard Foerster, Brendan Higgins) Changes from v13 (https://lore.kernel.org/linux-mm/20200525091512.30391-1-sjpark@xxxxxxxxxx/) - Fix a typo (Leonard Foerster) - Fix wring condition of three sub ranges split (Leonard Foerster) - Rebase on v5.7 Changes from v12 (https://lore.kernel.org/linux-mm/20200518100018.2293-1-sjpark@xxxxxxxxxx/) - Avoid races between debugfs readers and writers - Add kernel-doc comments in damon.h Changes from v11 (https://lore.kernel.org/linux-mm/20200511123302.12520-1-sjpark@xxxxxxxxxx/) - Rewrite the document (Stefan Nuernberger) - Make 'damon_for_each_*' argument order consistent (Leonard Foerster) - Fix wrong comment in 'kdamond_merge_regions()' (Leonard Foerster) Changes from v10 (https://lore.kernel.org/linux-mm/20200505110815.10532-1-sjpark@xxxxxxxxxx/) - Reduce aggressive split overhead by doing it only if required Changes from v9 (https://lore.kernel.org/linux-mm/20200427120442.24179-1-sjpark@xxxxxxxxxx/) - Split each region into 4 subregions if possible (Jonathan Cameraon) - Update kunit test for the split code change Changes from v8 (https://lore.kernel.org/linux-mm/20200406130938.14066-1-sjpark@xxxxxxxxxx/) - Make regions always aligned by minimal region size that can be changed (Stefan Nuernberger) - Store binary format version in the recording file (Stefan Nuernberger) - Use 'int' for pid instead of 'unsigned long' (Stefan Nuernberger) - Fix a race condition in damon thread termination (Stefan Nuernberger) - Optimize random value generation and recording (Stefan Nuernberger) - Clean up commit messages and comments (Stefan Nuernberger) - Clean up code (Stefan Nuernberger) - Use explicit signalling and 'do_exit()' for damon thread termination - Add more typos to spelling.txt - Update the performance evaluation results - Describe future plans in the cover letter Please refer to the v8 patchset to get older history. SeongJae Park (14): mm/page_ext: Export lookup_page_ext() to GPL modules mm: Introduce Data Access MONitor (DAMON) mm/damon: Implement region based sampling mm/damon: Adaptively adjust regions mm/damon: Apply dynamic memory mapping changes mm/damon: Implement callbacks mm/damon: Implement access pattern recording mm/damon: Add debugfs interface mm/damon: Add tracepoints tools: Add a minimal user-space tool for DAMON Documentation/admin-guide/mm: Add a document for DAMON mm/damon: Add kunit tests mm/damon: Add user space selftests MAINTAINERS: Update for DAMON Documentation/admin-guide/mm/damon/api.rst | 20 + .../admin-guide/mm/damon/damon_heatmap.png | Bin 0 -> 8366 bytes .../admin-guide/mm/damon/damon_wss_change.png | Bin 0 -> 7211 bytes .../admin-guide/mm/damon/damon_wss_dist.png | Bin 0 -> 6173 bytes Documentation/admin-guide/mm/damon/eval.rst | 215 +++ Documentation/admin-guide/mm/damon/faq.rst | 46 + .../admin-guide/mm/damon/freqmine_heatmap.png | Bin 0 -> 8687 bytes .../admin-guide/mm/damon/freqmine_wss_sz.png | Bin 0 -> 4986 bytes .../mm/damon/freqmine_wss_time.png | Bin 0 -> 6283 bytes Documentation/admin-guide/mm/damon/guide.rst | 196 +++ Documentation/admin-guide/mm/damon/index.rst | 36 + .../admin-guide/mm/damon/mechanisms.rst | 111 ++ Documentation/admin-guide/mm/damon/plans.rst | 49 + Documentation/admin-guide/mm/damon/start.rst | 119 ++ .../mm/damon/streamcluster_heatmap.png | Bin 0 -> 37916 bytes .../mm/damon/streamcluster_wss_sz.png | Bin 0 -> 5522 bytes .../mm/damon/streamcluster_wss_time.png | Bin 0 -> 6322 bytes Documentation/admin-guide/mm/damon/usage.rst | 305 ++++ Documentation/admin-guide/mm/index.rst | 1 + MAINTAINERS | 12 + include/linux/damon.h | 136 ++ include/trace/events/damon.h | 43 + mm/Kconfig | 23 + mm/Makefile | 1 + mm/damon-test.h | 635 +++++++ mm/damon.c | 1554 +++++++++++++++++ mm/page_ext.c | 1 + tools/damon/.gitignore | 1 + tools/damon/_dist.py | 36 + tools/damon/_recfile.py | 23 + tools/damon/bin2txt.py | 67 + tools/damon/damo | 37 + tools/damon/heats.py | 362 ++++ tools/damon/nr_regions.py | 91 + tools/damon/record.py | 217 +++ tools/damon/report.py | 45 + tools/damon/wss.py | 97 + tools/testing/selftests/damon/Makefile | 7 + .../selftests/damon/_chk_dependency.sh | 28 + tools/testing/selftests/damon/_chk_record.py | 108 ++ .../testing/selftests/damon/debugfs_attrs.sh | 139 ++ .../testing/selftests/damon/debugfs_record.sh | 50 + 42 files changed, 4811 insertions(+) create mode 100644 Documentation/admin-guide/mm/damon/api.rst create mode 100644 Documentation/admin-guide/mm/damon/damon_heatmap.png create mode 100644 Documentation/admin-guide/mm/damon/damon_wss_change.png create mode 100644 Documentation/admin-guide/mm/damon/damon_wss_dist.png create mode 100644 Documentation/admin-guide/mm/damon/eval.rst create mode 100644 Documentation/admin-guide/mm/damon/faq.rst create mode 100644 Documentation/admin-guide/mm/damon/freqmine_heatmap.png create mode 100644 Documentation/admin-guide/mm/damon/freqmine_wss_sz.png create mode 100644 Documentation/admin-guide/mm/damon/freqmine_wss_time.png create mode 100644 Documentation/admin-guide/mm/damon/guide.rst create mode 100644 Documentation/admin-guide/mm/damon/index.rst create mode 100644 Documentation/admin-guide/mm/damon/mechanisms.rst create mode 100644 Documentation/admin-guide/mm/damon/plans.rst create mode 100644 Documentation/admin-guide/mm/damon/start.rst create mode 100644 Documentation/admin-guide/mm/damon/streamcluster_heatmap.png create mode 100644 Documentation/admin-guide/mm/damon/streamcluster_wss_sz.png create mode 100644 Documentation/admin-guide/mm/damon/streamcluster_wss_time.png create mode 100644 Documentation/admin-guide/mm/damon/usage.rst create mode 100644 include/linux/damon.h create mode 100644 include/trace/events/damon.h create mode 100644 mm/damon-test.h create mode 100644 mm/damon.c create mode 100644 tools/damon/.gitignore create mode 100644 tools/damon/_dist.py create mode 100644 tools/damon/_recfile.py create mode 100644 tools/damon/bin2txt.py create mode 100755 tools/damon/damo create mode 100644 tools/damon/heats.py create mode 100644 tools/damon/nr_regions.py create mode 100644 tools/damon/record.py create mode 100644 tools/damon/report.py create mode 100644 tools/damon/wss.py create mode 100644 tools/testing/selftests/damon/Makefile create mode 100644 tools/testing/selftests/damon/_chk_dependency.sh create mode 100644 tools/testing/selftests/damon/_chk_record.py create mode 100755 tools/testing/selftests/damon/debugfs_attrs.sh create mode 100755 tools/testing/selftests/damon/debugfs_record.sh -- 2.17.1
