VFS/driver core overhead

[nick]

Greetings All,
After reading through the code for the usb and vfs core infrastructure, I was wondering if 
after reading it if I am correct in my notion of there being very little overhead or none
at all int these areas of the kernel. This is due to be noticing most drivers and file 
systems wrap around the core/vfs and therefore the overhead is very little and no need
to worry about it like the overhead of the kernel's process structures based off task_struct
.Honestly, I could benchmark this area of the kernel but it's hard to remove the file 
system/drivers interfering with my benchmarks due to me not knowing of any one way to do that.
If someone either points me to a benchmark for me to test this or answers it that would be
very helpful.
Thanks,
Nick