atime on your own time

Many Linux file systems keep track of the last access time of every file. In practice this turns out to be very inefficient. Every time the file system reads from a file it must also write the access time back to the file. There’s a good thread on the atime issue over at kerneltrap. You may see performance gains by disabling atime There are reports of wildly different numbers in performance improvements. Here are my own non-scientific numbers.

I just finished rendering a video project I been working on in Cinerella. Rendering took slightly over 24 hours to complete. (Digital video editing isn’t exactly fast on any hardware)

Then to compare I decided to render the video again, but this time with atime disabled.

I added “noatime” to my /etc/fstab

/dev/hda1 UUID=XXX-XXX-XXX / ext3 defaults,noatime,data=writeback,errors=remount-ro 0 1

The next rendering took 22 hours. So in my case disabling atime gave me about a 9% speed increase. From now on I’ll be disabling atime on all my systems.