Docs/ABI/testing: add DAMON sysfs interface ABI document

This commit adds DAMON sysfs interface ABI document under
Documentation/ABI/testing.

Link: https://lkml.kernel.org/r/20220228081314.5770-14-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: Xin Hao <xhao@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 275 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-kernel-mm-damon b/Documentation/ABI/testing/sysfs-kernel-mm-damon
new file mode 100644
index 000000000000..9e282065cbcf
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-kernel-mm-damon
@@ -0,0 +1,274 @@
+what:		/sys/kernel/mm/damon/
+Date:		Mar 2022
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Interface for Data Access MONitoring (DAMON).  Contains files
+		for controlling DAMON.  For more details on DAMON itself,
+		please refer to Documentation/admin-guide/mm/damon/index.rst.
+
+What:		/sys/kernel/mm/damon/admin/
+Date:		Mar 2022
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Interface for privileged users of DAMON.  Contains files for
+		controlling DAMON that aimed to be used by privileged users.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/nr_kdamonds
+Date:		Mar 2022
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Writing a number 'N' to this file creates the number of
+		directories for controlling each DAMON worker thread (kdamond)
+		named '0' to 'N-1' under the kdamonds/ directory.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/state
+Date:		Mar 2022
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Writing 'on' or 'off' to this file makes the kdamond starts or
+		stops, respectively.  Reading the file returns the keywords
+		based on the current status.  Writing 'update_schemes_stats' to
+		the file updates contents of schemes stats files of the
+		kdamond.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/pid
+Date:		Mar 2022
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Reading this file returns the pid of the kdamond if it is
+		running.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/nr_contexts
+Date:		Mar 2022
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Writing a number 'N' to this file creates the number of
+		directories for controlling each DAMON context named '0' to
+		'N-1' under the contexts/ directory.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/operations
+Date:		Mar 2022
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Writing a keyword for a monitoring operations set ('vaddr' for
+		virtual address spaces monitoring, and 'paddr' for the physical
+		address space monitoring) to this file makes the context to use
+		the operations set.  Reading the file returns the keyword for
+		the operations set the context is set to use.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/monitoring_attrs/intervals/sample_us
+Date:		Mar 2022
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Writing a value to this file sets the sampling interval of the
+		DAMON context in microseconds as the value.  Reading this file
+		returns the value.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/monitoring_attrs/intervals/aggr_us
+Date:		Mar 2022
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Writing a value to this file sets the aggregation interval of
+		the DAMON context in microseconds as the value.  Reading this
+		file returns the value.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/monitoring_attrs/intervals/update_us
+Date:		Mar 2022
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Writing a value to this file sets the update interval of the
+		DAMON context in microseconds as the value.  Reading this file
+		returns the value.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/monitoring_attrs/nr_regions/min
+
+WDate:		Mar 2022
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Writing a value to this file sets the minimum number of
+		monitoring regions of the DAMON context as the value.  Reading
+		this file returns the value.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/monitoring_attrs/nr_regions/max
+Date:		Mar 2022
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Writing a value to this file sets the maximum number of
+		monitoring regions of the DAMON context as the value.  Reading
+		this file returns the value.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/targets/nr_targets
+Date:		Mar 2022
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Writing a number 'N' to this file creates the number of
+		directories for controlling each DAMON target of the context
+		named '0' to 'N-1' under the contexts/ directory.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/targets/<T>/pid_target
+Date:		Mar 2022
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Writing to and reading from this file sets and gets the pid of
+		the target process if the context is for virtual address spaces
+		monitoring, respectively.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/targets/<T>/regions/nr_regions
+Date:		Mar 2022
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Writing a number 'N' to this file creates the number of
+		directories for setting each DAMON target memory region of the
+		context named '0' to 'N-1' under the regions/ directory.  In
+		case of the virtual address space monitoring, DAMON
+		automatically sets the target memory region based on the target
+		processes' mappings.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/targets/<T>/regions/<R>/start
+Date:		Mar 2022
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Writing to and reading from this file sets and gets the start
+		address of the monitoring region.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/targets/<T>/regions/<R>/end
+Date:		Mar 2022
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Writing to and reading from this file sets and gets the end
+		address of the monitoring region.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/schemes/nr_schemes
+Date:		Mar 2022
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Writing a number 'N' to this file creates the number of
+		directories for controlling each DAMON-based operation scheme
+		of the context named '0' to 'N-1' under the schemes/ directory.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/schemes/<S>/action
+Date:		Mar 2022
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Writing to and reading from this file sets and gets the action
+		of the scheme.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/schemes/<S>/access_pattern/sz/min
+Date:		Mar 2022
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Writing to and reading from this file sets and gets the mimimum
+		size of the scheme's target regions in bytes.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/schemes/<S>/access_pattern/sz/max
+Date:		Mar 2022
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Writing to and reading from this file sets and gets the maximum
+		size of the scheme's target regions in bytes.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/schemes/<S>/access_pattern/nr_accesses/min
+Date:		Mar 2022
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Writing to and reading from this file sets and gets the manimum
+		'nr_accesses' of the scheme's target regions.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/schemes/<S>/access_pattern/nr_accesses/max
+Date:		Mar 2022
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Writing to and reading from this file sets and gets the maximum
+		'nr_accesses' of the scheme's target regions.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/schemes/<S>/access_pattern/age/min
+Date:		Mar 2022
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Writing to and reading from this file sets and gets the minimum
+		'age' of the scheme's target regions.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/schemes/<S>/access_pattern/age/max
+Date:		Mar 2022
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Writing to and reading from this file sets and gets the maximum
+		'age' of the scheme's target regions.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/schemes/<S>/quotas/ms
+Date:		Mar 2022
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Writing to and reading from this file sets and gets the time
+		quota of the scheme in milliseconds.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/schemes/<S>/quotas/bytes
+Date:		Mar 2022
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Writing to and reading from this file sets and gets the size
+		quota of the scheme in bytes.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/schemes/<S>/quotas/reset_interval_ms
+Date:		Mar 2022
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Writing to and reading from this file sets and gets the quotas
+		charge reset interval of the scheme in milliseconds.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/schemes/<S>/quotas/weights/sz_permil
+Date:		Mar 2022
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Writing to and reading from this file sets and gets the
+		under-quota limit regions prioritization weight for 'size' in
+		permil.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/schemes/<S>/quotas/weights/nr_accesses_permil
+Date:		Mar 2022
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Writing to and reading from this file sets and gets the
+		under-quota limit regions prioritization weight for
+		'nr_accesses' in permil.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/schemes/<S>/quotas/weights/age_permil
+Date:		Mar 2022
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Writing to and reading from this file sets and gets the
+		under-quota limit regions prioritization weight for 'age' in
+		permil.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/schemes/<S>/watermarks/metric
+Date:		Mar 2022
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Writing to and reading from this file sets and gets the metric
+		of the watermarks for the scheme.  The writable/readable
+		keywords for this file are 'none' for disabling the watermarks
+		feature, or 'free_mem_rate' for the system's global free memory
+		rate in permil.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/schemes/<S>/watermarks/interval_us
+Date:		Mar 2022
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Writing to and reading from this file sets and gets the metric
+		check interval of the watermarks for the scheme in
+		microseconds.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/schemes/<S>/watermarks/high
+Date:		Mar 2022
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Writing to and reading from this file sets and gets the high
+		watermark of the scheme in permil.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/schemes/<S>/watermarks/mid
+Date:		Mar 2022
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Writing to and reading from this file sets and gets the mid
+		watermark of the scheme in permil.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/schemes/<S>/watermarks/low
+Date:		Mar 2022
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Writing to and reading from this file sets and gets the low
+		watermark of the scheme in permil.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/schemes/<S>/stats/nr_tried
+Date:		Mar 2022
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Reading this file returns the number of regions that the action
+		of the scheme has tried to be applied.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/schemes/<S>/stats/sz_tried
+Date:		Mar 2022
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Reading this file returns the total size of regions that the
+		action of the scheme has tried to be applied in bytes.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/schemes/<S>/stats/nr_applied
+Date:		Mar 2022
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Reading this file returns the number of regions that the action
+		of the scheme has successfully applied.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/schemes/<S>/stats/sz_applied
+Date:		Mar 2022
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Reading this file returns the total size of regions that the
+		action of the scheme has successfully applied in bytes.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/schemes/<S>/stats/qt_exceeds
+Date:		Mar 2022
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Reading this file returns the number of the exceed events of
+		the scheme's quotas.
diff --git a/MAINTAINERS b/MAINTAINERS
index cd0f68d4a34a..a1352ba4663f 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -5317,6 +5317,7 @@ DATA ACCESS MONITOR
 M:	SeongJae Park <sj@kernel.org>
 L:	linux-mm@kvack.org
 S:	Maintained
+F:	Documentation/ABI/testing/sysfs-kernel-mm-damon
 F:	Documentation/admin-guide/mm/damon/
 F:	Documentation/vm/damon/
 F:	include/linux/damon.h