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Swappolube

The SWAPPOLUBE Editor is a graphical user interface to the configuration of several parameters of the N900 kernel with the aim to make it faster.

It provides the ability to change a number of parameters while in operation and if chosen will make them persistent by adding a script to event.d to set them after each boot.

It has been created with PyQT (PyQt v4.7.5 for Python v2.6) and the functionality is provided by Python.

The configuration options have been discussed in (at least) two talk.maemo.org threads: "How to set swappiness" and "Swappolube to lubricate your gui".

Contents 1 Installation 1.1 Dependencies 2 Usage 2.1 Main configuration 2.1.1 Current Button 2.1.2 Proposed Button 2.2 Drop down menu 2.3 Popup Menu 2.3.1 New Config Applied 2.3.2 New Config Created 2.3.3 Delete Tuning File 2.4 Credits 3 Explanation of options 3.1 Swappiness 3.2 Page Cluster 3.3 Laptop Mode 3.4 oom_kill_allocating_task 3.5 dirty_expire_centisecs 3.6 dirty_writeback_centisecs 3.7 dirty_background_ratio 3.8 dirty_ratio 3.9 tcp_timestamps 3.10 tcp_no_metrics_save 3.11 VFS Cache Pressure 4 Versions: 4.1 v.0.2.0-3 (current) 4.2 v.0.2.0-2 4.3 v.0.2.0-1 4.4 v.0.1.0-8 5 Future Development 6 Swappolube-nogui 7 License 8 Disclaimer

Installation

The application can be installed directly by the Application Manager (HAM) from the Extras repositories (check here for its status).

You can also find the latest version in the garage project page.

Dependencies

The editor depends (not verified yet) at:

• python2.5
• python2.5-qt4-gui
• python2.5-qt4-core
• python2.5-qt4-maemo5

Usage

When the application loads it reads and displays the current configuration and the options already used by the system and displays them in the appropriate sections of the GUI.

Main configuration

• The first row of checkboxes is to enable the setting. If unchecked it will not write anything for that option.
• The second row can offer either string entry or a checkbox.
  • String: integer value up to 4 digits.
  • Checkbox: if checked will give a "1", if not checked it's a "0" , i.e. True/False.

Current Button

Pressing the "Current" button will read and display the current configuration the system uses.

Proposed Button

Drop down menu

The drop down menu will offer the following options:

• Delete Tuning
• About
• Credits
• Quit

Popup Menu

Several popups inform the user on the action taken.

New Config Applied

New Config Created

Delete Tuning File

Credits

File:Swappolube credits.png

Explanation of options

Swappiness

• Description: The swappiness parameter controls the tendency of the kernel to move processes out of physical memory and onto the swap disk. Because disks are much slower than RAM, this can lead to slower response times for system and applications if processes are too aggressively moved out of memory. [1]
• Default: "100"
• Suggested: "30"
• echo "30" > /proc/sys/vm/swappiness

Page Cluster

• echo "0" > /proc/sys/vm/page-cluster

Laptop Mode

• Description: laptop_mode is a knob that controls "laptop mode". When the knob is set, any physical disk I/O (that might have caused the hard disk to spin up, see /proc/sys/vm/block_dump) causes Linux to flush all dirty blocks. The result of this is that after a disk has spun down, it will not be spun up anymore to write dirty blocks, because those blocks had already been written immediately after the most recent read operation. The value of the laptop_mode knob determines the time between the occurrence of disk I/O and when the flush is triggered. A sensible value for the knob is 5 seconds. Setting the knob to 0 disables laptop mode.
• Default: "0"
• Suggested: "1"
• echo "1" > /proc/sys/vm/laptop_mode

oom_kill_allocating_task

• Description:
• Default: ""
• Suggested: "1"
• echo "1" > /proc/sys/vm/oom_kill_allocating_task

dirty_expire_centisecs

• Description:
• Default: ""
• Suggested: "0"
• echo "0" > /proc/sys/vm/dirty_expire_centisecs

dirty_writeback_centisecs

• Description:
• Default: ""
• Suggested: "0"
• echo "0" > /proc/sys/vm/dirty_writeback_centisecs

dirty_background_ratio

• Description:
• Default: "10"
• Suggested: "60"
• echo "60" > /proc/sys/vm/dirty_background_ratio

dirty_ratio

• Description:
• Default: "40"
• Suggested: "95"
• echo "95" > /proc/sys/vm/dirty_ratio

tcp_timestamps

• Description:
• Default: ""
• Suggested: "0"
• echo "0" > /proc/sys/net/ipv4/tcp_timestamps

tcp_no_metrics_save

• Description:
• Default: ""
• Suggested: "1"
• echo "1" > /proc/sys/net/ipv4/tcp_no_metrics_save

VFS Cache Pressure

• Description:"Controls the tendency of the kernel to reclaim the memory which is used for caching of directory and inode objects.At the default value of vfs_cache_pressure = 100 the kernel will attempt to reclaim dentries and inodes at a "fair" rate with respect to pagecache and swapcache reclaim. Decreasing vfs_cache_pressure causes the kernel to prefer to retain dentry and inode caches. Increasing vfs_cache_pressure beyond 100 causes the kernel to prefer to reclaim dentries and inodes."
• Default: "100"
• Suggested: "100" (in search)
• echo "100" > /proc/sys/vm/vfs_cache_pressure

Versions:

v.0.2.0-3 (current)

• changelog:
  • Fix in the update of the VFSCachePressure value. Previous version did not store this correctly.
  • Fix in the reading of values from the system. A hiden linebreak (shown as space) was added in all values after hitting "Current" which blocked their later update.

• issues:
  • none known/reported.

v.0.2.0-2

• changelog:
  • Change of the Laptop Mode setting to string.
  • Updated description.
  • Some UI changes - beautifications.

v.0.2.0-1

• changelog:
  • Added two new buttons (current & proposed) to set the settings in the GUI.
  • Added icons for the application manager and the desktop.
  • Many code changes/splits in methods.
  • Added several protections when handling updates.
  • Fixed in GUI directional errors.
  • Constrained the entry values to 4 digits.

v.0.1.0-8

• changelog:
  • New button to update the settings.
  • Transformed several fields from boolean to strings.

NOTE: For older versions please see the changelogs in the garage page

Future Development

Note: Just thoughts, not confirmed.

• Read the current configuration stored in the tuning script and automatically display it.
• Store/Read the configuration from a file (easy for sharing).
• Decide a more appropriate name.

Swappolube-nogui

For those who don't want to tinker too much with kernel parameters, the package swappolube-nogui provides a fixed tuning profile "known to work". Kernel parameters are modified at installation time, and the modification persist at the next boots. Package removal reverts parameters to the default values. The swappolube-nogui package conflicts with the swappolube package because both use the same script /etc/event.d/tuning for persistence. The common application managers should prompt for removal of one when trying to install the other.

• swappolube-nogui package status
• Garage project page.

License

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; version 2 only.

Disclaimer

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.