$ make
CC bench/sched-pipe.o
bench/sched-pipe.c: In function 'bench_sched_pipe':
bench/sched-pipe.c:58:6: error: variable 'ret' set but not used [-Werror=unused-but-set-variable]
cc1: all warnings being treated as errors
make: *** [bench/sched-pipe.o] Error 1
gcc version 4.6.0 20110331 (Red Hat 4.6.0-2) (GCC)