DAMOS fitlers are exclusive filters. It only excludes memory of given criterias from the DAMOS action targets. This has below limitations. First, the name is not explicitly explaining the behavior. This actually resulted in users' confusions[1]. Secondly, combined uses of multiple filters provide only restriced coverages. For example, building a DAMOS scheme that applies the action to memory that belongs to cgroup A "or" cgroup B is impossible. A workaround would be using two schemes that fitlers out memory that not belong to cgroup A and cgroup B, respectively. It is cumbersome, and difficult to control quota-like per-scheme features in an orchestration. Monitoring of filters-passed memory statistic will also be complicated. Extend DAMOS filters to support not only exclusion (rejecting), but also inclusion (allowing) behavior. For this, add a new damos_filter struct field called 'allow' for DAMON kernel API users. The filter works as an inclusion or exclusion filter when it is set or unset, respectively. For DAMON user-space ABI users, add a DAMON sysfs file of same name under DAMOS filter sysfs directory. To prevent exposing a behavioral change to old users, set rejecting as the default behavior. Note that allow-filters work for only inclusion, not exclusion of memory that not satisfying the criteria. And the default behavior of DAMOS for memory that no filter has involved is that the action can be applied to those memory. Also, filters-passed memory statistics are for any memory that passed through the DAMOS filters check stage. These implies installing allow-filters at the endof the filter list is useless. Refer to the design doc change of this series for more details. [1] https://lore.kernel.org/20240320165619.71478-1-sj@xxxxxxxxxx Revision History ================ Changes from v1 (https://lore.kernel.org/20250107201739.79484-1-sj@xxxxxxxxxx) - Correct wrong comments and documents about pass filters without successing block filters - Rename 'pass/block' to 'allow/reject' (to avoid confusion with sz_[ops]_filter_pass) Changes from RFC v2 (https://lore.kernel.org/20241227210819.63776-1-sj@xxxxxxxxxx) - Wordsmith messages - Wordsmith design documentation about monitoring-purpose usage - Rebase on latest mm-unstable Changes from RFC v1 (https://lore.kernel.org/20241226221445.78433-1-sj@xxxxxxxxxx) - Fix encoding issue on the last patch SeongJae Park (10): mm/damon: fixup damos_filter kernel-doc mm/damon/core: add damos_filter->allow field mm/damon/core: support damos_filter->allow mm/damon/paddr: support damos_filter->allow mm/damon: add 'allow' argument to damos_new_filter() mm/damon/sysfs-schemes: add a file for setting damos_filter->allow Docs/mm/damon/design: document allow/reject DAMOS filter behaviors Docs/ABI/damon: document DAMOS filter allow sysfs file Docs/admin-guide/mm/damon/usage: omit DAMOS filter details in favor of design doc Docs/admin-guide/mm/damon/usage: document DAMOS filter 'allow' sysfs file .../ABI/testing/sysfs-kernel-mm-damon | 13 +++-- Documentation/admin-guide/mm/damon/usage.rst | 54 ++++++++++--------- Documentation/mm/damon/design.rst | 33 ++++++++++-- include/linux/damon.h | 15 +++--- mm/damon/core.c | 12 +++-- mm/damon/paddr.c | 9 ++-- mm/damon/reclaim.c | 2 +- mm/damon/sysfs-schemes.c | 32 ++++++++++- mm/damon/tests/core-kunit.h | 14 ++--- 9 files changed, 127 insertions(+), 57 deletions(-) -- 2.39.5
