tb_now            131 tools/testing/selftests/powerpc/benchmarks/null_syscall.c 	unsigned long tb_start, tb_now;
tb_now            143 tools/testing/selftests/powerpc/benchmarks/null_syscall.c 	tb_now = mftb();
tb_now            147 tools/testing/selftests/powerpc/benchmarks/null_syscall.c 	elapsed_tb = tb_now - tb_start;