135 lines
6.2 KiB
ReStructuredText
135 lines
6.2 KiB
ReStructuredText
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.. SPDX-License-Identifier: GPL-2.0
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===============
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Getting Started
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===============
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This document briefly describes how you can use DAMON by demonstrating its
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default user space tool. Please note that this document describes only a part
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of its features for brevity. Please refer to the usage `doc
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<https://github.com/awslabs/damo/blob/next/USAGE.md>`_ of the tool for more
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details.
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Prerequisites
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=============
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Kernel
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------
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You should first ensure your system is running on a kernel built with
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``CONFIG_DAMON_*=y``.
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User Space Tool
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---------------
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For the demonstration, we will use the default user space tool for DAMON,
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called DAMON Operator (DAMO). It is available at
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https://github.com/awslabs/damo. The examples below assume that ``damo`` is on
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your ``$PATH``. It's not mandatory, though.
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Because DAMO is using the debugfs interface (refer to :doc:`usage` for the
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detail) of DAMON, you should ensure debugfs is mounted. Mount it manually as
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below::
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# mount -t debugfs none /sys/kernel/debug/
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or append the following line to your ``/etc/fstab`` file so that your system
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can automatically mount debugfs upon booting::
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debugfs /sys/kernel/debug debugfs defaults 0 0
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Recording Data Access Patterns
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==============================
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The commands below record the memory access patterns of a program and save the
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monitoring results to a file. ::
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$ git clone https://github.com/sjp38/masim
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$ cd masim; make; ./masim ./configs/zigzag.cfg &
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$ sudo damo record -o damon.data $(pidof masim)
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The first two lines of the commands download an artificial memory access
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generator program and run it in the background. The generator will repeatedly
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access two 100 MiB sized memory regions one by one. You can substitute this
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with your real workload. The last line asks ``damo`` to record the access
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pattern in the ``damon.data`` file.
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Visualizing Recorded Patterns
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=============================
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You can visualize the pattern in a heatmap, showing which memory region
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(x-axis) got accessed when (y-axis) and how frequently (number).::
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$ sudo damo report heats --heatmap stdout
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22222222222222222222222222222222222222211111111111111111111111111111111111111100
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44444444444444444444444444444444444444434444444444444444444444444444444444443200
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44444444444444444444444444444444444444433444444444444444444444444444444444444200
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33333333333333333333333333333333333333344555555555555555555555555555555555555200
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33333333333333333333333333333333333344444444444444444444444444444444444444444200
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22222222222222222222222222222222222223355555555555555555555555555555555555555200
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00000000000000000000000000000000000000288888888888888888888888888888888888888400
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00000000000000000000000000000000000000288888888888888888888888888888888888888400
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33333333333333333333333333333333333333355555555555555555555555555555555555555200
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88888888888888888888888888888888888888600000000000000000000000000000000000000000
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88888888888888888888888888888888888888600000000000000000000000000000000000000000
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33333333333333333333333333333333333333444444444444444444444444444444444444443200
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00000000000000000000000000000000000000288888888888888888888888888888888888888400
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[...]
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# access_frequency: 0 1 2 3 4 5 6 7 8 9
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# x-axis: space (139728247021568-139728453431248: 196.848 MiB)
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# y-axis: time (15256597248362-15326899978162: 1 m 10.303 s)
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# resolution: 80x40 (2.461 MiB and 1.758 s for each character)
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You can also visualize the distribution of the working set size, sorted by the
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size.::
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$ sudo damo report wss --range 0 101 10
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# <percentile> <wss>
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# target_id 18446632103789443072
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# avr: 107.708 MiB
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0 0 B | |
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10 95.328 MiB |**************************** |
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20 95.332 MiB |**************************** |
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30 95.340 MiB |**************************** |
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40 95.387 MiB |**************************** |
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50 95.387 MiB |**************************** |
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60 95.398 MiB |**************************** |
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70 95.398 MiB |**************************** |
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80 95.504 MiB |**************************** |
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90 190.703 MiB |********************************************************* |
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100 196.875 MiB |***********************************************************|
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Using ``--sortby`` option with the above command, you can show how the working
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set size has chronologically changed.::
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$ sudo damo report wss --range 0 101 10 --sortby time
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# <percentile> <wss>
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# target_id 18446632103789443072
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# avr: 107.708 MiB
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0 3.051 MiB | |
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10 190.703 MiB |***********************************************************|
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20 95.336 MiB |***************************** |
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30 95.328 MiB |***************************** |
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40 95.387 MiB |***************************** |
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50 95.332 MiB |***************************** |
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60 95.320 MiB |***************************** |
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70 95.398 MiB |***************************** |
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80 95.398 MiB |***************************** |
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90 95.340 MiB |***************************** |
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100 95.398 MiB |***************************** |
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Data Access Pattern Aware Memory Management
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===========================================
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Below three commands make every memory region of size >=4K that doesn't
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accessed for >=60 seconds in your workload to be swapped out. ::
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$ echo "#min-size max-size min-acc max-acc min-age max-age action" > test_scheme
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$ echo "4K max 0 0 60s max pageout" >> test_scheme
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$ damo schemes -c test_scheme <pid of your workload>
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