Linux File Systems Visualized
by Michael Hay on Jun 20, 2009
The images above are taken directly from the author’s, Răzvan Musăloiu-E, site that takes us on this journey into the Linux file system internals. His exploration is done by looking at the number of external symbols per file system type. I think that there are a number of interesting points from the analysis. One is that the fewer the symbols the more self contained the file system is. Further the more modern file systems like btrfs, ext4 and xfs all have many external symbols. Perhaps this means that more and more of the code needed to generate a file system is making its way into the kernel and associated libraries resulting in it being easier to create new file systems on the Linux platform? Finally if you look at some of the visuals you will find that btrfs and xfs are often in close proximity to one another, I’m not sure what this means, but it is interesting none the less.
I just got permission to use some of Răzvan images and conversed with the author of the study via email, I do want to point out the following point:
Me: … the increase of dependence on external symbols is there any conclusion we can draw from this? In particular I’m wondering if more functions have been finding their way into the Linux kernel making it easier to create file systems on Linux than other platforms.
Răzvan: If things would be really easy then I would expect the interactions between the file systems and kernel to be limited in number and see that most of the system are using most of them. This is not the case though. Just by looking from outside we can see that there are quite a lot of them. There is the chance that these big number is also inflated by inlining.
Thanks for the permission and discourse Răzvan!
[...] I reported in the previous post there are some interesting things going on when we look at btrfs and xfs. The first thing that I [...]