IO class id,IO class name,Eviction priority,Allocation
0,Unclassified,22,1
1,Superblock,0,1
2,GroupDesc,1,1
3,BlockBitmap,2,1
4,InodeBitmap,3,1
5,Inode,4,1
6,IndirectBlk,5,1
7,Directory,6,1
8,Journal,7,1
10,Xatrr,8,1
11,<=4KiB,9,1
12,<=16KiB,10,1
13,<=64KiB,11,1
14,<=256KiB,12,1
15,<=1MiB,13,1
16,<=4MiB,14,1
17,<=16MiB,15,1
18,<=64MiB,16,1
19,<=256MiB,17,1
20,<=1GiB,18,1
21,>1GiB,19,1
22,O_DIRECT,20,1
23,Misc,21,1