The patch titled
Subject: Docs/mm/damon/design: document allow/reject DAMOS filter behaviors
has been added to the -mm mm-unstable branch. Its filename is
docs-mm-damon-design-document-allow-reject-damos-filter-behaviors.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/docs-mm-damon-design-document-allow-reject-damos-filter-behaviors.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: SeongJae Park <sj@xxxxxxxxxx>
Subject: Docs/mm/damon/design: document allow/reject DAMOS filter behaviors
Date: Thu, 9 Jan 2025 09:51:23 -0800
Update DAMOS filters design document to describe the allow/reject behavior
of filters.
Link: https://lkml.kernel.org/r/20250109175126.57878-8-sj@xxxxxxxxxx
Signed-off-by: SeongJae Park <sj@xxxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/mm/damon/design.rst | 33 ++++++++++++++++++++++++----
1 file changed, 29 insertions(+), 4 deletions(-)
--- a/Documentation/mm/damon/design.rst~docs-mm-damon-design-document-allow-reject-damos-filter-behaviors
+++ a/Documentation/mm/damon/design.rst
@@ -504,9 +504,34 @@ have a list of latency-critical processe
To let users optimize DAMOS schemes with such special knowledge, DAMOS provides
a feature called DAMOS filters. The feature allows users to set an arbitrary
-number of filters for each scheme. Each filter specifies the type of target
-memory, and whether it should exclude the memory of the type (filter-out), or
-all except the memory of the type (filter-in).
+number of filters for each scheme. Each filter specifies
+
+- a type of memory (``type``),
+- whether it is for the memory of the type or all except the type
+ (``matching``), and
+- whether it is to allow (include) or reject (exclude) applying
+ the scheme's action to the memory (``allow``).
+
+When multiple filters are installed, each filter is evaluated in the installed
+order. If a part of memory is matched to one of the filter, next filters are
+ignored. If the memory passes through the filters evaluation stage because it
+is not matched to any of the filters, applying the scheme's action to it is
+allowed, same to the behavior when no filter exists.
+
+For example, let's assume 1) a filter for allowing anonymous pages and 2)
+another filter for rejecting young pages are installed in the order. If a page
+of a region that eligible to apply the scheme's action is an anonymous page,
+the scheme's action will be applied to the page regardless of whether it is
+young or not, since it matches with the first allow-filter. If the page is
+not anonymous but young, the scheme's action will not be applied, since the
+second reject-filter blocks it. If the page is neither anonymous nor young,
+the page will pass through the filters evaluation stage since there is no
+matching filter, and the action will be applied to the page.
+
+Note that the action can equally be applied to memory that either explicitly
+filter-allowed or filters evaluation stage passed. It means that installing
+allow-filters at the end of the list makes no practical change but only
+filters-checking overhead.
For efficient handling of filters, some types of filters are handled by the
core layer, while others are handled by operations set. In the latter case,
@@ -516,7 +541,7 @@ filter are not counted as the scheme has
a memory regions is filtered by an operations set layer-handled filter, it is
counted as the scheme has tried. This difference affects the statistics.
-Below types of filters are currently supported.
+Below ``type`` of filters are currently supported.
- anonymous page
- Applied to pages that containing data that not stored in files.
_
Patches currently in -mm which might be from sj@xxxxxxxxxx are
samples-add-a-skeleton-of-a-sample-damon-module-for-working-set-size-estimation.patch
samples-damon-wsse-start-and-stop-damon-as-the-user-requests.patch
samples-damon-wsse-implement-working-set-size-estimation-and-logging.patch
samples-damon-introduce-a-skeleton-of-a-smaple-damon-module-for-proactive-reclamation.patch
samples-damon-prcl-implement-schemes-setup.patch
replace-free-hugepage-folios-after-migration-fix-2.patch
mm-damon-sysfs-schemes-remove-unnecessary-schemes-existence-check-in-damon_sysfs_schemes_clear_regions.patch
mm-damon-sysfs-handle-clear_schemes_tried_regions-from-damon-sysfs-context.patch
mm-damon-core-introduce-damon_call.patch
mm-damon-sysfs-use-damon_call-for-update_schemes_stats.patch
mm-damon-sysfs-use-damon_call-for-commit_schemes_quota_goals.patch
mm-damon-sysfs-use-damon_call-for-update_schemes_effective_quotas.patch
mm-damon-core-implement-damos_walk.patch
docs-mm-damon-design-document-damos-regions-walking.patch
mm-damon-sysfs-use-damos_walk-for-update_schemes_tried_bytesregions.patch
mm-damon-sysfs-remove-unused-code-for-schemes-tried-regions-update.patch
mm-damon-clarify-trying-vs-applying-on-damos_stat-kernel-doc-comment.patch
docs-mm-damon-design-add-statistics-section.patch
docs-admin-guide-mm-damon-usage-link-damos-stat-design-doc.patch
mm-damon-ask-apply_scheme-to-report-filter-passed-region-internal-bytes.patch
mm-damon-paddr-report-filter-passed-bytes-back-for-normal-actions.patch
mm-damon-paddr-report-filter-passed-bytes-back-for-damos_stat-action.patch
mm-damon-core-implement-per-scheme-ops-handled-filter-passed-bytes-stat.patch
mm-damon-syfs-schemes-implement-per-scheme-filter-passed-bytes-stat.patch
docs-mm-damon-design-document-sz_ops_filter_passed.patch
docs-admin-guide-mm-damon-usage-document-sz_ops_filter_passed.patch
docs-abi-damon-document-per-scheme-filter-passed-bytes-stat-file.patch
mm-damon-core-pass-per-region-filter-passed-bytes-to-damos_walk_control-walk_fn.patch
mm-damon-sysfs-schemes-expose-per-region-filter-passed-bytes.patch
docs-mm-damon-design-document-per-region-sz_filter_passed-stat.patch
docs-admin-guide-mm-damon-usage-document-sz_filtered_out-of-scheme-tried-region-directories.patch
docs-abi-damon-document-per-region-damos-filter-passed-bytes-stat-file.patch
docs-translations-admin-guide-mm-damon-usage-remove-damon-debugfs-interface-documentation.patch
docs-admin-guide-mm-damon-usage-remove-damon-debugfs-interface-documentation.patch
docs-mm-damon-design-update-for-removal-of-damon-debugfs-interface.patch
selftests-damon-config-remove-configs-for-damon-debugfs-interface-selftests.patch
selftests-damon-remove-tests-for-damon-debugfs-interface.patch
kunit-configs-remove-configs-for-damon-debugfs-interface-tests.patch
mm-damon-remove-damon-debugfs-interface-kunit-tests.patch
mm-damon-remove-damon-debugfs-interface.patch
mm-damon-fixup-damos_filter-kernel-doc.patch
mm-damon-core-add-damos_filter-allow-field.patch
mm-damon-core-support-damos_filter-allow.patch
mm-damon-paddr-support-damos_filter-allow.patch
mm-damon-add-allow-argument-to-damos_new_filter.patch
mm-damon-sysfs-schemes-add-a-file-for-setting-damos_filter-allow.patch
docs-mm-damon-design-document-allow-reject-damos-filter-behaviors.patch
docs-abi-damon-document-damos-filter-allow-sysfs-file.patch
docs-admin-guide-mm-damon-usage-omit-damos-filter-details-in-favor-of-design-doc.patch
docs-admin-guide-mm-damon-usage-document-damos-filter-allow-sysfs-file.patch
