why no likely() and unlikely() used in Ceph's source code?

[Tim Zhang]

Hey guys,
After reading ceph source code, I find that there is a file named
common/likely.h and it implements the function likely() and unlikey() which
will optimize the prediction of code branch for cpu.
But there isn't any place using these two functions, I am curious
about why the developer of ceph not using these two functions to achieve
more performance. Can anyone provide some hints?
BR