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Slow disk access and overall speed issues in newer ubuntu and linux mint

April 10, 2017 Leave a comment

I have the subjective feeling that the newer versions of ubuntu and its derivatives including linux mint has slowed up a bit compared to pre unity ubuntus(11.04) or linux mint 17. I had been looking for the reason for some time. This probably won’t apply to you unless you are using a slow ‘hard disk’. The symptom is that subjectively the disk access latencies are larger (eg. applications take longer to start).

Linux has a software component called the IO scheduler. This takes care of scheduling requests to the permanent storage devices. There are a few choices for the algorithm to be used for this purpose. The choices and current selection can be seen by issuing

cat /sys/block/sda/queue/scheduler

(For me the sda is the drive containing all linux partitions. It may change for you ie. sda, sdb, sdc.. or hda, hdb, hdc…)

The default in modern ubuntu and linux mint is the ‘deadline‘ scheduler; probably a decision based on benchmark performance results on modern hardware. I changed this to ‘cfq‘, and subjectively the system became a lot more responsive. You can temporarily tryout the setting by writing the new scheduler name to the above file using command

sudo sh -c 'echo cfq > /sys/block/sda/queue/scheduler'

If you find think system responsiveness is better than before, you can make the changes permanent by writing following settings to /etc/default/grub and running update-grub2

sudo vim /etc/default/grub

Type the setting

GRUB_CMDLINE_LINUX="elevator=cfq"

Exit editor.

update-grub2

From next reboot onwards the setting should now takeplace at boot itself.

Must use tools for Electronics/Electrical Students

ToolsHere is a list of computer based tools, which i know or have used and felt to be great and must-use for every elctrical/electronics engineering students. Priorities are price, ease of use on multiple platforms, popularity etc..

Analog/Power Electronic Circuts – LTspice (works smoothly in wine)
Antenna Design – MMANA-GAL
C/C++ IDE – Code::Blocks (linux & win versions available. use the installer with mingw, if you want compilers also installed)
Embedded Development – SDCC (8051), WinAvr (AVR)
Networking – WireShark (have both linux and win versions)
Numerical Simulations, Visualisation – Octave (great on linux, with QtOctave), Matlab (non free), Scilab. Scilab’s language is a bit different from the other two.

There are many other tools like KiCad that are worth giving a try. For digital circuit simulation, evaluation/student version of many softwares are available. In addition to these, I have used tools for PCB layout etc, which I don’t remember the name. sourceforge.net is a good place to search for authentic free softwares.

Install Firefox 4 on Ubuntu

May 11, 2011 2 comments

Firefox 4 is catching on. Still Ubuntu has not put this in its stable repositories, for the older versions. Newbies in Ubuntu will find installing Firefox 4 difficult. This describes the method I used to install Firefox 4.

First download Firefox 4 from the official site. The downloaded file will be an archive named firefox-4.0.1.tar.bz2. Extract the archive file by right click and extract here. A folder firefox will be created. Inside this folder, a file firefox is present. Give execute permission to this file by typing sudo a+x firefox/firefox.

Double clicking the file will open a message box. Choose Run in the message box. This will open the Firefox 4.0 browser. This is the simple way of using Firefox 4.

A neater way is to move the folder firefox either to a separate folder for programs in your home folder, or to the /usr/local/ directory. For the former, running the firefox file inside the firefox folder is enough. Moving the folder to /usr/local will require root’s permissions. Type sudo mv firefox /usr/local to move the folder to /usr/local/

The older version can be removed using synaptic, which leads to a broken application launcher in the top panel. Right click on it, and choose properties, browse for the firefox file or enter its path correctly. The command that I have to use will hence beĀ usr/local/firefox/firefox %u, as I have moved the folder firefox to /usr/local Click on the icon on the left choose firefox/icons/mozicon128.png. Click on the launcher to launch Firefox 4.0