C++11 auto and decltype Explained

Very well explained by Thomas Becker.

http://thbecker.net/articles/auto_and_decltype/section_01.html

Ubuntu 12.10: Disable touchpad of Lenovo Thinkpad

Thinkpads come with a red-dot mouse option, as well as, the standard trackpad. I love the red-dot because I do not need to move my fingers all around to trackpad to move the mouse. I feel more comfortable using the red-dot as the mouse. But problem is that when you use the red-dot, quite-often than not, your palm touches the trackpad which will cause sudden movements in the mouse. I wanted a way to disable the trackpad completely and only use the red-dot as the mouse.

Fortunately, I found this tutorial on the web. Following it was a breeze, and I was able to quickly disable the trackpad.

sudo takes a long time on ubuntu 12.10 after installing kerberos client

I recently installed Ubuntu Desktop 12.10 on my new office laptop. I also installed kerberos client since we use it for authentication for some common services. But since then, sudo started taking long time when I work from home.

After digging for information, I found in /var/log/auth.log that pam_krb5() authentication is failing because it is unable to contact the KDC server!

Fixed it by editing /etc/pam.d/common-auth and commenting the following line

auth [success=2 default=ignore]    pam_krb5.so minimum_uid=1000

Are unaligned reads really expensive?

Are unaligned reads really expensive?

  Since college days, I had come to understand that processor is very good at reading data which is aligned at word boundaries. Any unaligned memory read is considered to be slower. But when I recently saw such a read operation in a piece of code, I was trying to optimize, I was surprised to see no change in the performance after removing the unaligned read operation. After Googling on the same, found the following article

http://lemire.me/blog/archives/2012/05/31/data-alignment-for-speed-myth-or-reality/

  It turns out that modern Intel processors handle unaligned reads, as efficiently as, aligned memory reads.

Note: This is applicable to Intel processors only.