From: SeongJae Park <sjpark@xxxxxxxxx> Changes from Previous Version ============================= - Drop loadable module support (Mike Rapoport) - Select PAGE_EXTENSION if !64BIT for 'set_page_young()' - Take care of the MMU notification subscribers (Shakeel Butt) - Substitute 'struct damon_task' with 'struct damon_target' for better abstract - Use 'struct pid' instead of 'pid_t' as the target (Shakeel Butt) - Support pidfd from the debugfs interface (Shakeel Butt) - Fix typos (Greg Thelen) - Properly isolate DAMON from other pmd/pte Accessed bit users (Greg Thelen) - Rebase on v5.8 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 v16 DAMON patchset is applied. DAMON is lightweight. It increases system memory usage by only -0.25% and consumes less than 1% CPU time in most case. It slows target workloads down by only 0.94%. DAMON is accurate and useful for memory management optimizations. An experimental DAMON-based operation scheme for THP, 'ethp', removes 31.29% of THP memory overheads while preserving 60.64% of THP speedup. Another experimental DAMON-based 'proactive reclamation' implementation, 'prcl', reduces 87.95% of residential sets and 29.52% of system memory footprint while incurring only 2.15% 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/admin-guide/mm/damon/eval.html 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/rec.heatmap.0.png.html [4] https://damonitor.github.io/test/result/visual/latest/rec.heatmap.1.png.html [5] https://damonitor.github.io/test/result/visual/latest/rec.heatmap.2.png.html [6] https://damonitor.github.io/test/result/visual/latest/rec.wss_sz.png.html [7] https://damonitor.github.io/test/result/visual/latest/rec.wss_time.png.html [8] https://damonitor.github.io/test/result/perf/latest/html/index.html Baseline and Complete Git Trees =============================== The patches are based on the v5.8. You can also clone the complete git tree: $ git clone git://github.com/sjp38/linux -b damon/patches/v19 The web is also available: https://github.com/sjp38/linux/releases/tag/damon/patches/v19 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 =================== First four patches implement the target address space independent core logics of DAMON and it's programming interface. The 1st patch introduces DAMON subsystem, it's data structures, and the data structure related basic manipulation functions. Following three patches (2nd to 4th) implements the core mechanisms of DAMON, namely regions based sampling (patch 2), adaptive regions adjustment (patch 3), and dynamic memory mapping change adoption (patch 4). Now the essential parts of DAMON is complete but require low level primitives to be implemented and configured with DAMON to just work. The following two patches makes it just work for virtual address spaces monitoring. The 5th patch makes 'PG_idle' could be used by DAMON and the 6th patch implements the virtual memory address space specific low primitives using page table Accessed bits and the 'PG_idle' page flag. Now DAMON just works for virtual address space monitoring via the kernel space api. Following six patches adds interfaces for the users in the user space. The 7th patch implements recording of access patterns in DAMON. Each of next two patches (8th and 9th) respectively adds a tracepoint for other tracepoints supporting tracers such as perf, and a debugfs interface for privileged people and/or programs in user space. 10th patch makes the debugfs interface further support pidfd. And, the 11th patch implements an user space tool to provide a minimal reference to the debugfs interface and for high level use/tests of the DAMON. Three patches for maintainability follows. The 12th patch adds documentations for both the user space and the kernel space. The 13th patch provides unit tests (based on the kunit) while the 14th patch adds user space tests (based on the kselftest). Finally, the last patch (15th) updates the MAINTAINERS file. Patch History ============= Changes from v18 (https://lore.kernel.org/linux-mm/20200713084144.4430-1-sjpark@xxxxxxxxxx/) - Drop loadable module support (Mike Rapoport) - Select PAGE_EXTENSION if !64BIT for 'set_page_young()' - Take care of the MMU notification subscribers (Shakeel Butt) - Substitute 'struct damon_task' with 'struct damon_target' for better abstract - Use 'struct pid' instead of 'pid_t' as the target (Shakeel Butt) - Support pidfd from the debugfs interface (Shakeel Butt) - Fix typos (Greg Thelen) - Properly isolate DAMON from other pmd/pte Accessed bit users (Greg Thelen) - Rebase on v5.8 Changes from v17 (https://lore.kernel.org/linux-mm/20200706115322.29598-1-sjpark@xxxxxxxxxx/) - Reorganize the doc and remove png blobs (Mike Rapoport) - Wordsmith mechnisms doc and commit messages - tools/wss: Set default working set access frequency threshold - Avoid race in damon deamon start Changes from v16 (https://lore.kernel.org/linux-mm/20200615161927.12637-1-sjpark@xxxxxxxxxx/) - Wordsmith/cleanup the documentations and the code - user space tool: Simplify the code and add wss option for reuse histogram - recording: Check disablement condition properly - recording: Force minimal recording buffer size (1KB) Changes from v15 (https://lore.kernel.org/linux-mm/20200608114047.26589-1-sjpark@xxxxxxxxxx/) - Refine commit messages (David Hildenbrand) - Optimizes three vma regions search (Varad Gautam) - Support static granularity monitoring (Shakeel Butt) - Cleanup code and re-organize the sequence of patches 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 Please refer to the v13 patchset to get older history. SeongJae Park (15): mm: Introduce Data Access MONitor (DAMON) mm/damon: Implement region based sampling mm/damon: Adaptively adjust regions mm/damon: Track dynamic monitoring target regions update mm/idle_page_tracking: Make PG_(idle|young) reusable mm/damon: Implement callbacks for the virtual memory address spaces mm/damon: Implement access pattern recording mm/damon: Add a tracepoint mm/damon: Implement a debugfs interface damon/debugfs: Support pidfd target id tools: Introduce a minimal user-space tool for DAMON Documentation: Add documents for DAMON mm/damon: Add kunit tests mm/damon: Add user space selftests MAINTAINERS: Update for DAMON Documentation/admin-guide/mm/damon/guide.rst | 157 ++ Documentation/admin-guide/mm/damon/index.rst | 15 + Documentation/admin-guide/mm/damon/plans.rst | 29 + Documentation/admin-guide/mm/damon/start.rst | 96 + Documentation/admin-guide/mm/damon/usage.rst | 302 +++ Documentation/admin-guide/mm/index.rst | 1 + Documentation/vm/damon/api.rst | 20 + Documentation/vm/damon/design.rst | 166 ++ Documentation/vm/damon/eval.rst | 222 +++ Documentation/vm/damon/faq.rst | 58 + Documentation/vm/damon/index.rst | 31 + Documentation/vm/index.rst | 1 + MAINTAINERS | 13 + include/linux/damon.h | 188 ++ include/linux/page-flags.h | 4 +- include/linux/page_ext.h | 2 +- include/linux/page_idle.h | 6 +- include/trace/events/damon.h | 43 + include/trace/events/mmflags.h | 2 +- mm/Kconfig | 33 + mm/Makefile | 1 + mm/damon-test.h | 671 +++++++ mm/damon.c | 1732 +++++++++++++++++ mm/page_ext.c | 12 +- mm/page_idle.c | 10 - tools/damon/.gitignore | 1 + tools/damon/_damon.py | 130 ++ 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 | 135 ++ tools/damon/report.py | 45 + tools/damon/wss.py | 100 + tools/testing/selftests/damon/Makefile | 7 + .../selftests/damon/_chk_dependency.sh | 28 + tools/testing/selftests/damon/_chk_record.py | 109 ++ .../testing/selftests/damon/debugfs_attrs.sh | 161 ++ .../testing/selftests/damon/debugfs_record.sh | 50 + 41 files changed, 5179 insertions(+), 18 deletions(-) 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/plans.rst create mode 100644 Documentation/admin-guide/mm/damon/start.rst create mode 100644 Documentation/admin-guide/mm/damon/usage.rst create mode 100644 Documentation/vm/damon/api.rst create mode 100644 Documentation/vm/damon/design.rst create mode 100644 Documentation/vm/damon/eval.rst create mode 100644 Documentation/vm/damon/faq.rst create mode 100644 Documentation/vm/damon/index.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/_damon.py 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
