[2007-08-08] Disabling atime Updates

A recent article on KernelTrap highlights the high cost of supporting atime ("last-accessed time") updates on Linux file-systems. It has been suggested that desktop machines should just mount their file-systems using the "noatime" option to avoid this overhead.

Each time you read a file, its atime has to be updated. This can quickly become costly if you have applications that access a lot of small files. Most modern desktop environments, office suites, compilers (think of C/C++ headers), browsers, etc. fall into this category, so Linux takes a lot of unnecessary performance hit for data that is of interest only to a very small set of applications like tmpwatch. (Apparently even Windows has the same issue with NTFS.)

I have now changed the "/etc/fstab" on my PC to mount its file-systems using the "noatime" option. It does seem to have slightly improved the responsiveness of the desktop, though this could just be a placebo effect. On the other hand, in the KernelTrap article people have presented measurements that demonstrate the actual performance improvements brought about by using this option.

(Originally posted on Blogspot.)

Other Posts from 2007