这东西实验性还是很强 在编译过程中 出现很多错误，

最后一次忽略所有错误继续 编译 才编译过去，

读

time dd if=/mnt/hdfs/user/root/with_country.tsv/part-00071  of=/tmp/a.txt bs=8k count=30000

3603+1 records in

3603+1 records out

29519802 bytes (30 MB) copied, 2.98445 s, 9.9 MB/s

real 0m3.015s

user 0m0.008s

sys 0m0.104s

写

sudo time dd if=/dev/zero of=/mnt/hdfs/test.txt bs=8k count=3000

3000+0 records in

3000+0 records out

24576000 bytes (25 MB) copied, 2.98638 s, 8.2 MB/s

0.00user 0.08system 0:03.01elapsed 2%CPU (0avgtext+0avgdata 0maxresident)k

0inputs+0outputs (0major+261minor)pagefaults 0swaps

~$ sudo time dd if=/dev/zero of=/mnt/hdfs/test.txt bs=8k count=30000

30000+0 records in

30000+0 records out

245760000 bytes (246 MB) copied, 30.1176 s, 8.2 MB/s

0.03user 0.78system 0:30.19elapsed 2%CPU (0avgtext+0avgdata 0maxresident)k

0inputs+0outputs (0major+259minor)pagefaults 0swaps