From 68536f8e01e571f553f78fa058ba543de3834452 Mon Sep 17 00:00:00 2001 From: SeongJae Park Date: Fri, 5 Nov 2021 13:46:39 -0700 Subject: Docs/admin-guide/mm/damon: document DAMON-based Operation Schemes This adds the description of DAMON-based operation schemes in the DAMON documents. Link: https://lkml.kernel.org/r/20211001125604.29660-8-sj@kernel.org Signed-off-by: SeongJae Park Cc: Amit Shah Cc: Benjamin Herrenschmidt Cc: David Hildenbrand Cc: David Rienjes Cc: David Woodhouse Cc: Greg Thelen Cc: Jonathan Cameron Cc: Jonathan Corbet Cc: Leonard Foerster Cc: Marco Elver Cc: Markus Boehme Cc: Shakeel Butt Cc: Shuah Khan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/admin-guide/mm/damon/start.rst | 11 ++++++ Documentation/admin-guide/mm/damon/usage.rst | 51 ++++++++++++++++++++++++++-- 2 files changed, 60 insertions(+), 2 deletions(-) (limited to 'Documentation/admin-guide') diff --git a/Documentation/admin-guide/mm/damon/start.rst b/Documentation/admin-guide/mm/damon/start.rst index d5eb89a8fc38..51503cf90ca2 100644 --- a/Documentation/admin-guide/mm/damon/start.rst +++ b/Documentation/admin-guide/mm/damon/start.rst @@ -108,6 +108,17 @@ the results as separate image files. :: You can view the visualizations of this example workload at [1]_. Visualizations of other realistic workloads are available at [2]_ [3]_ [4]_. + +Data Access Pattern Aware Memory Management +=========================================== + +Below three commands make every memory region of size >=4K that doesn't +accessed for >=60 seconds in your workload to be swapped out. :: + + $ echo "#min-size max-size min-acc max-acc min-age max-age action" > scheme + $ echo "4K max 0 0 60s max pageout" >> scheme + $ damo schemes -c my_thp_scheme + .. [1] https://damonitor.github.io/doc/html/v17/admin-guide/mm/damon/start.html#visualizing-recorded-patterns .. [2] https://damonitor.github.io/test/result/visual/latest/rec.heatmap.1.png.html .. [3] https://damonitor.github.io/test/result/visual/latest/rec.wss_sz.png.html diff --git a/Documentation/admin-guide/mm/damon/usage.rst b/Documentation/admin-guide/mm/damon/usage.rst index a72cda374aba..c0296c14babf 100644 --- a/Documentation/admin-guide/mm/damon/usage.rst +++ b/Documentation/admin-guide/mm/damon/usage.rst @@ -34,8 +34,8 @@ the reason, this document describes only the debugfs interface debugfs Interface ================= -DAMON exports three files, ``attrs``, ``target_ids``, and ``monitor_on`` under -its debugfs directory, ``/damon/``. +DAMON exports four files, ``attrs``, ``target_ids``, ``schemes`` and +``monitor_on`` under its debugfs directory, ``/damon/``. Attributes @@ -74,6 +74,53 @@ check it again:: Note that setting the target ids doesn't start the monitoring. +Schemes +------- + +For usual DAMON-based data access aware memory management optimizations, users +would simply want the system to apply a memory management action to a memory +region of a specific size having a specific access frequency for a specific +time. DAMON receives such formalized operation schemes from the user and +applies those to the target processes. It also counts the total number and +size of regions that each scheme is applied. This statistics can be used for +online analysis or tuning of the schemes. + +Users can get and set the schemes by reading from and writing to ``schemes`` +debugfs file. Reading the file also shows the statistics of each scheme. To +the file, each of the schemes should be represented in each line in below form: + + min-size max-size min-acc max-acc min-age max-age action + +Note that the ranges are closed interval. Bytes for the size of regions +(``min-size`` and ``max-size``), number of monitored accesses per aggregate +interval for access frequency (``min-acc`` and ``max-acc``), number of +aggregate intervals for the age of regions (``min-age`` and ``max-age``), and a +predefined integer for memory management actions should be used. The supported +numbers and their meanings are as below. + + - 0: Call ``madvise()`` for the region with ``MADV_WILLNEED`` + - 1: Call ``madvise()`` for the region with ``MADV_COLD`` + - 2: Call ``madvise()`` for the region with ``MADV_PAGEOUT`` + - 3: Call ``madvise()`` for the region with ``MADV_HUGEPAGE`` + - 4: Call ``madvise()`` for the region with ``MADV_NOHUGEPAGE`` + - 5: Do nothing but count the statistics + +You can disable schemes by simply writing an empty string to the file. For +example, below commands applies a scheme saying "If a memory region of size in +[4KiB, 8KiB] is showing accesses per aggregate interval in [0, 5] for aggregate +interval in [10, 20], page out the region", check the entered scheme again, and +finally remove the scheme. :: + + # cd /damon + # echo "4096 8192 0 5 10 20 2" > schemes + # cat schemes + 4096 8192 0 5 10 20 2 0 0 + # echo > schemes + +The last two integers in the 4th line of above example is the total number and +the total size of the regions that the scheme is applied. + + Turning On/Off -------------- -- cgit