kernel/linux.git/tools/testing/selftests/damon/sysfs.py, branch v7.2-rc5

selftests/damon/sysfs.py: stop kdamonds before failing

2026-06-04T21:45:01+00:00

When an assertion is failed, sysfs.py DAMON selftest immediately exits the test program leaving the DAMON running behind. Many of the following tests need to start DAMON on their own. But because DAMON that was started by sysfs.py is still running, those start attempts fail, and the tests are failed or skipped. Update sysfs.py to stop DAMON before exiting the test program due to the assertion failure. Link: https://lore.kernel.org/20260522154026.80546-12-sj@kernel.org Signed-off-by: SeongJae Park Cc: Brendan Higgins Cc: Shuah Khan Signed-off-by: Andrew Morton

selftests/damon/sysfs.py: pause DAMON before dumping status

2026-05-29T04:05:00+00:00

The sysfs.py test commits DAMON parameters, dump the internal DAMON state, and show if the parameters are committed as expected using the dumped state. While the dumping is ongoing, DAMON is alive. It can make internal changes including addition and removal of regions. It can therefore make a race that can result in false test results. Pause DAMON execution during the state dumping to avoid such races. Link: https://lore.kernel.org/20260427151231.113429-11-sj@kernel.org Signed-off-by: SeongJae Park Cc: Brendan Higgins Cc: David Hildenbrand Cc: Jonathan Corbet Cc: Liam R. Howlett Cc: Lorenzo Stoakes Cc: Michal Hocko Cc: Mike Rapoport Cc: Shuah Khan Cc: Suren Baghdasaryan Cc: Vlastimil Babka Signed-off-by: Andrew Morton

selftests/damon/sysfs.py: check pause on assert_ctx_committed()

2026-05-29T04:04:59+00:00

Extend sysfs.py tests to confirm damon_ctx->pause can be set using the pause sysfs file. Link: https://lore.kernel.org/20260427151231.113429-10-sj@kernel.org Signed-off-by: SeongJae Park Cc: Brendan Higgins Cc: David Hildenbrand Cc: Jonathan Corbet Cc: Liam R. Howlett Cc: Lorenzo Stoakes Cc: Michal Hocko Cc: Mike Rapoport Cc: Shuah Khan Cc: Suren Baghdasaryan Cc: Vlastimil Babka Signed-off-by: Andrew Morton

mm/damon: support MADV_COLLAPSE via DAMOS_COLLAPSE scheme action

2026-05-29T04:04:56+00:00

This patch set introces a new action: DAMOS_COLLAPSE. For DAMOS_HUGEPAGE and DAMOS_NOHUGEPAGE to work, khugepaged should be working, since it relies on hugepage_madvise to add a new slot. This slot should be picked up by khugepaged and eventually collapse (or not, if we are using DAMOS_NOHUGEPAGE) the pages. If THP is not enabled, khugepaged will not be working, and therefore no collapse will happen. DAMOS_COLLAPSE eventually calls madvise_collapse, which will collapse the address range synchronously. In cases where there is a large VMA (databases, for example), DAMOS_COLLAPSE allows us to collapse only the hot region, and not the entire VMA. This new action may be required to support autotuning with hugepage as a goal[1]. ========= Benchmarks: ========= MySQL ===== Tests were performed in an ARM physical server with MariaDB 10.5 and sysbench. Read only benchmark was perform with gaussian row hitting, which follows a normal distribution. T n, D h: THP set to never, DAMON action set to hugepage T m, D h: THP set to madvise, DAMON action set to hugepage T n, D c: THP set to never, DAMON action set to collapse Memory consumption. Lower is better. +------------------+----------+----------+----------+ | | T n, D h | T m, D h | T n, D c | +------------------+----------+----------+----------+ | Total memory use | 2.13 | 2.20 | 2.20 | | Huge pages | 0 | 1.3 | 1.27 | +------------------+----------+----------+----------+ Performance in TPS (Transactions Per Second). Higher is better. T n, D h: 18225.58 T m, D h 18252.93 T n, D c: 18270.21 Performance counter I got the number of L1 D/I TLB accesses and the number a D/I TLB accesses that triggered a page walk. I divided the second by the first to get the percentage of page walkes per TLB access. The lower the better. +---------------+--------------+--------------+--------------+ | | T n, D h | T m, D h | T n, D c | +---------------+--------------+--------------+--------------+ | L1 DTLB | 127248242753 | 125431020479 | 125327001821 | | L1 ITLB | 80332558619 | 79346759071 | 79298139590 | | DTLB walk | 75011087 | 52800418 | 55895794 | | ITLB walk | 71577076 | 71505137 | 67262140 | | DTLB % misses | 0.058948623 | 0.042095183 | 0.044599961 | | ITLB % misses | 0.089100954 | 0.090117275 | 0.084821839 | +---------------+--------------+--------------+--------------+ Masim ===== I used masim with the "demo" configuration, but changing the times to 100 seconds for the initial phase and 50 seconds for the rest of the phases. Memory consumption: +------------------+----------+----------+----------+ | | T n, D h | T m, D h | T n, D c | +------------------+----------+----------+----------+ | Total memory use | 2.38 GB | 2.36 GB | 2.37 GB | | Huge pages | 0 | 190 MB | 188 MB | +------------------+----------+----------+----------+ Performance: THP never, DAMOS_HUGEPAGE initial phase: 40,491 accesses/msec, 100001 msecs run low phase 0: 39,658 accesses/msec, 50002 msecs run high phase 0: 41,678 accesses/msec, 50000 msecs run low phase 1: 39,625 accesses/msec, 50003 msecs run high phase 1: 41,658 accesses/msec, 50002 msecs run low phase 2: 39,642 accesses/msec, 50002 msecs run high phase 2: 41,640 accesses/msec, 50001 msecs run THP madvise, DAMOS_HUGEPAGE initial phase: 51,977 accesses/msec, 100000 msecs run low phase 0: 86,953 accesses/msec, 50000 msecs run high phase 0: 94,812 accesses/msec, 50000 msecs run low phase 1: 101,017 accesses/msec, 50000 msecs run high phase 1: 94,841 accesses/msec, 50000 msecs run low phase 2: 100,993 accesses/msec, 50000 msecs run high phase 2: 94,791 accesses/msec, 50001 msecs run THP never, DAMOS_COLLAPSE initial phase: 93,678 accesses/msec, 100001 msecs run low phase 0: 101,475 accesses/msec, 50000 msecs run high phase 0: 98,589 accesses/msec, 50000 msecs run low phase 1: 101,531 accesses/msec, 50001 msecs run high phase 1: 98,506 accesses/msec, 50001 msecs run low phase 2: 101,458 accesses/msec, 50001 msecs run high phase 2: 98,555 accesses/msec, 50000 msecs run Memory consumption dynamic (how quickly collapses occur): It shows in seconds how many huge pages are allocated. +----+----------+----------+ | | T m, D h | T n, D c | +----+----------+----------+ | 5 | 32 | 188 | | 10 | 48 | 188 | | 15 | 64 | 188 | | 20 | 96 | 188 | | 30 | 112 | 188 | | 35 | 144 | 188 | | 40 | 160 | 188 | | 45 | 190 | 188 | | 50 | 190 | 188 | | 55 | 190 | 188 | | 60 | 190 | 188 | +----+----------+----------+ ========= - We can see that DAMOS "hugepage" action works only when THP is set to madvise. "collapse" action works even when THP is set to never. - Performance for "collapse" action is slightly lower than "hugepage" action and THP madvise. This is due to the fact that collapases occur synchronously. With "hugepage" they may occur during page faults. - Memory consumption is slighly lower for "collapse" than "hugepage" with THP madvise. This is due to the khugepage collapses all VMAs, while "collapse" action only collapses the VMAs in the hot region. - There is an improvement in TLB utilization when collapse through "hugepage" or "collapse" actions are triggered. The amount of TLB misses is lower. - "collapse" action is performance synchronously, which means that page collapses happen earlier and more rapidly. This can be useful or not, depending on the scenario. - "hugepage" action may trigger a VMA split in some scenarios, since it needs to change the flag of the VMA to THP enabled. This may lead to additional overhead. Collapse action just adds a new option to chose the correct system balance. Link: https://lore.kernel.org/20260426231619.107231-5-sj@kernel.org Link: https://lore.kernel.org/damon/20260313000816.79933-1-sj@kernel.org/ [1] Signed-off-by: Asier Gutierrez Signed-off-by: SeongJae Park Reviewed-by: SeongJae Park Cc: Cheng-Han Wu Cc: David Hildenbrand Cc: Jonathan Corbet Cc: Liam R. Howlett Cc: Liew Rui Yan Cc: Lorenzo Stoakes Cc: Michal Hocko Cc: Mike Rapoport Cc: Shuah Khan Cc: Suren Baghdasaryan Cc: Vlastimil Babka Signed-off-by: Andrew Morton

selftests/damon/sysfs.py: test failed region quota charge ratio

2026-05-29T04:04:45+00:00

Extend sysfs.py DAMON selftest to setup DAMOS action failed region quota charge ratio and assert the setup is made into DAMON internal state. Link: https://lore.kernel.org/20260428013402.115171-12-sj@kernel.org Signed-off-by: SeongJae Park Cc: Brendan Higgins Cc: David Hildenbrand Cc: Jonathan Corbet Cc: Liam R. Howlett Cc: Lorenzo Stoakes Cc: Michal Hocko Cc: Mike Rapoport Cc: Shuah Khan Cc: Suren Baghdasaryan Cc: Vlastimil Babka Signed-off-by: Andrew Morton

selftests/damon/sysfs.py: test goal_tuner commit

2026-04-05T20:53:26+00:00

Extend the near-full DAMON parameters commit selftest to commit goal_tuner and confirm the internal status is updated as expected. Link: https://lkml.kernel.org/r/20260310010529.91162-12-sj@kernel.org Signed-off-by: SeongJae Park Signed-off-by: Andrew Morton

selftests/damon/sysfs.py: merge DAMON status dumping into commitment assertion

2025-11-20T21:44:01+00:00

For each test case, sysfs.py makes changes to DAMON, dumps DAMON internal status and asserts the expectation is met. The dumping part should be the same for all cases, so it is duplicated for each test case. Which means it is easy to make mistakes. Actually a few of those duplicates are not turning DAMON off in case of the dumping failure. It makes following selftests that need to turn DAMON on fails with -EBUSY. Merge the status dumping into commitment assertion with proper dumping failure handling, to deduplicate and avoid the unnecessary following tests failures. Link: https://lkml.kernel.org/r/20251112154114.66053-8-sj@kernel.org Signed-off-by: SeongJae Park Cc: Bill Wendling Cc: Brendan Higgins Cc: David Gow Cc: David Hildenbrand Cc: Hugh Dickins Cc: Jonathan Corbet Cc: Justin Stitt Cc: Liam Howlett Cc: Lorenzo Stoakes Cc: Michal Hocko Cc: Miguel Ojeda Cc: Mike Rapoport Cc: Nathan Chancellor Cc: Shuah Khan Cc: Suren Baghdasaryan Cc: Vlastimil Babka Signed-off-by: Andrew Morton

mm/damon: rename damos->filters to damos->core_filters

2025-11-20T21:44:01+00:00

DAMOS filters that are handled by the ops layer are linked to damos->ops_filters. Owing to the ops_ prefix on the name, it is easy to understand it is for ops layer handled filters. The other types of filters, which are handled by the core layer, are linked to damos->filters. Because of the name, it is easy to confuse the list is there for not only core layer handled ones but all filters. Avoid such confusions by renaming the field to core_filters. Link: https://lkml.kernel.org/r/20251112154114.66053-3-sj@kernel.org Signed-off-by: SeongJae Park Cc: Bill Wendling Cc: Brendan Higgins Cc: David Gow Cc: David Hildenbrand Cc: Hugh Dickins Cc: Jonathan Corbet Cc: Justin Stitt Cc: Liam Howlett Cc: Lorenzo Stoakes Cc: Michal Hocko Cc: Miguel Ojeda Cc: Mike Rapoport Cc: Nathan Chancellor Cc: Shuah Khan Cc: Suren Baghdasaryan Cc: Vlastimil Babka Signed-off-by: Andrew Morton

selftests/damon/sysfs: add obsolete_target test

2025-11-17T01:28:25+00:00

A new DAMON sysfs file for pin-point target removal, namely obsolete_target, has been added. Add a test for the functionality. It starts DAMON with three monitoring target processes, mark one in the middle as obsolete, commit it, and confirm the internal DAMON status is updated to remove the target in the middle. Link: https://lkml.kernel.org/r/20251023012535.69625-10-sj@kernel.org Signed-off-by: SeongJae Park Cc: Bijan Tabatabai Cc: David Hildenbrand Cc: Jonathan Corbet Cc: Liam Howlett Cc: Lorenzo Stoakes Cc: Michal Hocko Cc: Mike Rapoport Cc: Shuah Khan Cc: Suren Baghdasaryan Cc: Vlastimil Babka Signed-off-by: Andrew Morton

sysfs.py: extend assert_ctx_committed() for monitoring targets

2025-11-17T01:28:25+00:00

assert_ctx_committed() is not asserting monitoring targets commitment, since all existing callers of the function assume no target changes. Extend it for future usage. Link: https://lkml.kernel.org/r/20251023012535.69625-9-sj@kernel.org Signed-off-by: SeongJae Park Cc: Bijan Tabatabai Cc: David Hildenbrand Cc: Jonathan Corbet Cc: Liam Howlett Cc: Lorenzo Stoakes Cc: Michal Hocko Cc: Mike Rapoport Cc: Shuah Khan Cc: Suren Baghdasaryan Cc: Vlastimil Babka Signed-off-by: Andrew Morton