Using smem on Android

smem is a handy tool for analyzing system memory.

Quick steps

Here are some quick steps:

* download smem
   * hg clone http://selenic.com/repo/smem
   * cd smem
(install python-matplotlib and python-matplotlib-tk, if needed)
* cross-compile smemcap for Android, using something like 'agcc'
   * agcc smemcap.c -o android-smemcap
* install android-smemcap onto your target
   * adb shell mkdir /data/smem
   * adb push android-smemcap /data/smem
* collect memory information on target
   * adb shell "/data/smem/android-smemcap >/data/smem/data1.tar"
* retreive the collected data
   * adb pull /data/smem/data1.tar .
* review the data on host
   * smem -S data1.tar

This document describes how to use 'smem' with Android.

Introduction

smem is a memory tool for analyzing the amount of memory usage on a Linux system. The 'ps' tool provided with Android only shows the VSIZE and RSS memory columns. Even if you install busybox on an android system, that tool's 'ps' will also only show you only the VSIZE value. VSIZE is the total size of the virtual image, and RSS is the resident set size - the amount of physical pages accounted by the kernel to a particular process. These numbers are not very useful to indicate the actual cost in memory of a particular application or daemon.

From the smem web site (http://www.selenic.com/smem/):

"smem is a tool that can give numerous reports on memory usage on Linux systems. Unlike existing tools, smem can report proportional set size (PSS), which is a more meaningful representation of the amount of memory used by libraries and applications in a virtual memory system.

Because large portions of physical memory are typically shared among multiple applications, the standard measure of memory usage known as resident set size (RSS) will significantly overestimate memory usage. PSS instead measures each application's "fair share" of each shared area to give a realistic measure. of the activity of a system during boot."

smem consists of a data capture tool, for use on an android target, and an analysis tool for use on a development host machine.

Overview of Steps to Use smem

To use smem on an Android System, you need to perform the following steps:

* install the smem tool on your host machine
* build smemcap on your host machine (or use a pre-built binary)
* install smemcap on your Android target system
* use smemcap to capture the memory information from /proc on the target
* retrieve the collected data from the system
* use the smem tool with the collected data, on the host
* view memory information and charts
* [optionally] provide additional system information

These steps will be described in detail in the following sections. This paper was written based on Android 1.5 software and SDK.

Detailed Instructions

Installing the smem tool

smem can be downloaded from http://selenic.com/repo/smem

Download using the mercurial tool (hg)

{{{

   $ hg clone http://selenic.com/repo/smem

destination directory: smem requesting all changes adding changesets adding manifests adding file changes added 37 changesets with 40 changes to 5 files 5 files updated, 0 files merged, 0 files removed, 0 files unresolved }}}

This will create a directory called 'smem' in the current directory.

Usually, you will want to place the 'smem' program on your path. This can be done by copying smem to /usr/local/bin, like so (as root): {{{

   $ cp smem/smem /usr/local/bin

}}}

smem has a few requirements:

   * a reasonably modern kernel (> 2.6.27 or so)
   * a reasonably recent version of Python (2.4 or so)

The smem tool can be used in text mode with no further installation.

However, smem also provides the ability to produce nice charts and graphs. For this, it needs the python matplotlib plotting library.

On Fedora, you can install this (if it is not already installed) with the commands: {{{

  $ yum install python-matplotlib
  $ yum install python-matplotlib-tk

}}}

Other Linux distributions may also have packages for matplotlib.

Here are links to information if you need to directly download and/or install matplotlib

* http://matplotlib.sourceforge.net/index.html - home page
* http://sourceforge.net/projects/matplotlib - download area
* http://matplotlib.sourceforge.net/users/installing.html - install instructions

Building 'smemcap' (or use pre-built binary)

To collect the memory information from the /proc filesystem on the target you need to run the 'smemcap' program. smem also includes a shell script called 'capture' which can collect the data on a standard Linux desktop. However, the Android environment does not have the necessary shell environment or command line tools for this program to work. So you will need to use the compiled C program.

Compile the smemcap program as a native Android program against the bionic C library. Details about this are outside the scope of this document, but you can use the instructions here: Compiling Native Apps for Android

If you have installed 'agcc', then the following steps should work: {{{

  $ cd smem
  $ agcc smemcap.c -o android-smemcap

}}}

Alternatively, you can use a pre-built capture program. There is one attached to the bottom of this page: 'android-smemcap'.

Installing 'android-smemcap' onto your Android target

To install the android-smemcap program on your target, you just need to copy the program, and make sure it is executable. It is recommended to make a separate directory for smem capture data, on the /data portion of the target file system. (However, any writable directory can be used, such as one on an sdcard.)

Make the smem directory, copy the file: {{{

  $ adb shell mkdir /data/smem
  $ adb push android-smemcap /data/smem

}}}

You should check that the program is executable: {{{

  $ adb shell ls -l /data/smem

-rwxrwxrwx root root 7391 2009-06-24 14:47 android-smemcap }}}

Collect memory information on the target

Now, to measure the memory usage on the target, use the android-smemcap program to collect the data from the /proc filesystem.

{{{

  $ adb shell
  $ cd /data/smem
  $ ./android-smemcap >memdata1.tar
  $ exit

}}}

You can also do this directly from the host, using the adb shell: {{{

  $ adb shell "/data/smem/android-smemcap >/data/smem/memdata1.tar"

}}}

Note the use of quotes to have the shell redirection on the target stay on the target. Due to the binary nature of the data output by android-smemcap, you can not redirect it directly through the 'adb shell' command to the host filesystem.

Retrieving the collected data from the system

Now, collect the data from the target, and retrieve it to the host: {{{

   $ adb pull /data/smem/memdata1.tar .

}}}

This will pull the just-created file 'test1.tar' from the target and place it in the current directory.

Review the data on the host

Now, you can use the smem tool on the host, to view the target process data:

{{{

  $ smem -S memdata1.tar
 PID User     Command                         Swap      USS      PSS      RSS
  32 0        /system/bin/debuggerd              0       64       70      252
  30 1000     /system/bin/servicemanager         0       80       86      264
  36 1002     /system/bin/dbus-daemon --s        0       92      106      368
  39 0        /system/bin/sh /runme.sh           0       72      106      316
  37 0        /system/bin/installd               0      100      108      332
2462 0        /system/bin/sh -                   0       84      118      332
  31 0        /system/bin/vold                   0      136      144      392
  41 0        /sbin/adbd                         0      144      144      156
   1 0        /init                              0      152      154      172
3780 0        ./android-smemcap                  0      188      195      384
  40 1008     /system/bin/akmd                   0      268      303      688
  33 0        /system/bin/rild                   0      444      504      984
  35 1013     /system/bin/mediaserver            0      876     1458     2948
 181 0        com.android.voicedialer            0      948     1550    10668
 263 0        com.instamapper.gpstracker         0     1072     1633    10992
 252 0        com.rerware.android.MyBacku        0     1080     1665    11348
 289 0        com.android.music                  0     1204     1892    11436
 271 0        com.biggu.shopsavvy                0     1236     2050    12344
 241 0        com.android.alarmclock             0     1488     2087    12264
 215 0        com.android.email                  0     1524     2164    12116
 302 0        com.google.android.gm              0     1508     2170    11928
 280 0        com.acme.android.powermanag        0     1884     2533    12688
 135 0        com.android.mms                    0     2036     2711    12708
 164 0        android.process.media              0     2208     2840    13076
 412 0        com.biggu.shopsavvy:remote         0     2036     2904    13668
 228 0        com.android.calendar               0     2296     3005    13596
  34 0        zygote /bin/app_process -Xz        0     1088     3218    16688
 202 0        com.google.android.apps.map        0     2472     3334    14324
 106 0        com.android.phone                  0     4928     5891    16664
 155 0        com.google.process.gapps           0     4628     5933    17408
 108 0        android.process.acore              0     7288     9023    29560
  66 0        system_server                      0    10188    12636    35056

}}}

Viewing information and charts

There are a number of interesting options that smem provides, for filtering, analyzing and visualizing the process data.

Here are some interesting options:

* smem -S memdata1.tar --pie=command
  * Produces a pie chart labeled by the command names (with pss as the data key)
  * See below for a sample
*  smem -S memdata1.tar -P com.* --pie=command
  * Produce a pie chart, only showing Android applications (apps starting with "com.")
* smem -S memdata1.tar --bar=command
  * Produce a bar chart
  * See below for a sample
* smem -S memdata1.tar -m
  * Show all memory mappings on the system
* * smem -S memdata1.tar -m -P email
  * Show the mappings for the 'email' application
* smem -S memdata1.tar -m -M /system/lib/*
  * Show the system libraries
* smem -S memdata1.tar -m -M .*.apk
  * Show maps for application packages
* smem -S memdata1.tar -m -M lib -s pids
  * find the libraries with the most users
  * (ie. show mappings for libraries, with 'lib' in the name, sorted by number of processes (pids) using them.)

{{{ Map PIDs AVGPSS PSS /system/lib/hw/copybit.msm7k.so 1 8 8 /system/lib/hw/lights.msm7k.so 1 8 8 /system/lib/hw/sensors.trout.so 1 12 12 /system/lib/libagl.so 1 48 48 /system/lib/libandroid_servers.so 1 16 16 /system/lib/libhtc_acoustic.so 1 4 4 /system/lib/libhtc_ril.so 1 168 168 /system/lib/libril.so 1 28 28 /system/lib/libsoundpool.so 1 4 4 /system/lib/libsurfaceflinger.so 1 108 108 /system/lib/libsystem_server.so 1 8 8 /system/lib/liba2dp.so 2 6 12 /system/lib/libaudio.so 2 14 28 /system/lib/libaudioflinger.so 2 62 124 /system/lib/libcamera.so 2 14 28 /system/lib/libcameraservice.so 2 20 40 /system/lib/libmediaplayerservice.so 2 52 104 /system/lib/libmedia_jni.so 19 1 35 /system/lib/libwebcore.so 19 10 191 /system/lib/libEGL.so 20 0 15 /system/lib/libGLESv1_CM.so 20 0 12 /system/lib/libOmxCore.so 20 0 4 /system/lib/libaes.so 20 0 4 /system/lib/libandroid_runtime.so 20 13 267 /system/lib/libbluedroid.so 20 0 8 /system/lib/libcorecg.so 20 2 52 /system/lib/libcrypto.so 20 21 424 /system/lib/libdrm1.so 20 0 7 /system/lib/libdvm.so 20 18 375 /system/lib/libemoji.so 20 0 4 /system/lib/libhardware.so 20 0 7 /system/lib/libicudata.so 20 13 260 /system/lib/libicui18n.so 20 15 304 /system/lib/libicuuc.so 20 18 363 /system/lib/libmedia.so 20 5 102 /system/lib/libnativehelper.so 20 6 135 /system/lib/libopencoreauthor.so 20 13 265 /system/lib/libopencorecommon.so 20 9 185 /system/lib/libopencoreplayer.so 20 29 593 /system/lib/libpixelflinger.so 20 3 71 /system/lib/libsgl.so 20 29 583 /system/lib/libskiagl.so 20 0 4 /system/lib/libsonivox.so 20 0 7 /system/lib/libsqlite.so 20 16 325 /system/lib/libssl.so 20 4 97 /system/lib/libui.so 20 12 245 /system/lib/libvorbisidec.so 20 4 94 /system/lib/libdbus.so 21 0 16 /system/lib/libexpat.so 21 3 67 /system/lib/libgps.so 21 2 52 /system/lib/libhardware_legacy.so 21 1 40 /system/lib/libnetutils.so 21 0 16 /system/lib/librpc.so 21 0 16 /system/lib/libwpa_client.so 21 0 12 /system/lib/libutils.so 22 18 404 /system/lib/libz.so 22 3 77 /system/lib/libcutils.so 24 5 131 /system/lib/liblog.so 25 0 24 /system/lib/libstdc++.so 29 1 40 /system/lib/libc.so 30 14 444 /system/lib/libm.so 30 2 88 }}}

* smem -S memdata1.tar -M libc
  * Show processes using libc, (sorted by PSS)

{{{

 PID User     Command                         Swap      USS      PSS      RSS
 135 0        com.android.mms                    0        8       16      264
 164 0        android.process.media              0        8       16      264
 181 0        com.android.voicedialer            0        8       16      260
 202 0        com.google.android.apps.map        0        8       16      264
 215 0        com.android.email                  0        8       16      260
 228 0        com.android.calendar               0        8       16      264
 241 0        com.android.alarmclock             0        8       16      264
 252 0        com.rerware.android.MyBacku        0        8       16      260
 263 0        com.instamapper.gpstracker         0        8       16      260
 271 0        com.biggu.shopsavvy                0        8       16      260
 280 0        com.acme.android.powermanag        0        8       16      260
 289 0        com.android.music                  0        8       16      260
 302 0        com.google.android.gm              0        8       16      264
 412 0        com.biggu.shopsavvy:remote         0        8       16      264
  30 1000     /system/bin/servicemanager         0       16       19      124
  32 0        /system/bin/debuggerd              0       16       19      132
  39 0        /system/bin/sh /runme.sh           0       16       19      132
2462 0        /system/bin/sh -                   0       16       19      136
  36 1002     /system/bin/dbus-daemon --s        0       16       20      148
3780 0        ./android-smemcap                  0       16       20      144
  31 0        /system/bin/vold                   0       20       25      192
  37 0        /system/bin/installd               0       20       25      168
  40 1008     /system/bin/akmd                   0       20       25      176
 106 0        com.android.phone                  0       12       25      276
  33 0        /system/bin/rild                   0       20       30      204
 108 0        android.process.acore              0       16       36      312
  34 0        zygote /bin/app_process -Xz        0        8       83      472
  35 1013     /system/bin/mediaserver            0       44       95      344
 155 0        com.google.process.gapps           0       28      187      612
  66 0        system_server                      0       32      248      772

}}}

Sample Charts

Here are some examples of graphical charts produced by smem

• smem -S memdata1.tar --pie=command

  * Produces a pie chart labeled by the command names (with pss as the data key)

Image(test1-pie-command-pss.png)

* smem -S memdata1.tar --bar=command
  * Produce a bar chart

Image(test1-bar-command.png)

Providing addition system information

You can provide additional information to smem (such as the kernel image size), using the -R and -K options:

Here is an example showing the 'whole system' memory information, while specifing a kernel vmlinux image: {{{

  $ smem -S ftrace-kernel.tar -w -t -K /home/tbird/work/android/kernel-msm/build/g1/vmlinux

Area Used Cache Noncache firmware/hardware 0 0 0 kernel image 4515 0 4515 kernel dynamic memory 17500 4784 12716 userspace memory 78544 28736 49808 free memory 1988 1988 0

---

                            102547      35508      67039

}}}

In this example, my kernel was a test kernel that was significantly larger than a standard production kernel.

Using the graphical viewer

The graphical viewer provides options for zooming and panning portions of the graph, for adjusting graph display parameters, switching between views, and saving a view to an image file.

Here is a snapshot of the smem (matplotlib) chart viewer:

Here are some tips:

Sometimes it is difficult to read the chart labels. You can view the labels more easily if you pan and zoom the chart.

To zoom in on an area, click on the 'zoom to rectangle' button. Drag a rectangle in the viewing area. For a bar chart, the rectangle must reside within the graph area of the chart (above the x axis and to the right of the y axis). Once you unclick your mouse button, a zoomed image is then shown. You can pan the zoomed image by clicking the 'pan axes' button, and dragging the image with the left mouse button. (This "pan axes" button puts the chart in 'pan/zoom' mode. Click the button again to revert to regular view mode.)

You can also zoom using the right mouse button in the 'pan/zoom' mode.

You can adjust the location of the chart on the page (which is also sometimes necessary to see the full labels), by clicking on the "configure subplots" button. Experiment with changing different parameters, such as the bottom or left parameters.

Save a view to a file using the "save the figure" button. Select the image format to save in, from the drop-down list at the bottom of the dialog. Available formats are: bmp, eps, jpg, png, ps, svg.

Interpreting the results

See the smem web site for an explanation of USS and PSS, and how these measurements should be interpreted to analyze a running system.