Sysfs is a non-persistent virtual filesystem that provides a global view of the system and exposes the kernel object's hierarchy (topology) by means of their kobjects. Each kobject shows up as a directory, and files in a directory representing kernel variables, exported by the related kobject. These files are called attributes, and can be read or written.
Any registered kobject creates a directory in sysfs, where the directory is created depends on the kobject's parent (which is a kobject too). It is natural that directories are created as subdirectories of the kobject's parent. This highlights internal object hierarchies to the user space. Top-level directories in sysfs represent the common ancestors of object hierarchies, that is, the subsystems the objects belong to.
Top-level sysfs directories can be found under the /sys/ directory...
