Firefox is known to fsync its sqlite database aggressively; in a few short
seconds' runtime, witness:

# stap -g eatmydata.stp -c 'firefox'   
Redirecting f*sync by pid 10526 to fd -1
Redirected f*sync by pid 10526 to fd -1, success 19 times, failed 0 times.
Preserved f*sync by other processes 0 times.