Hi All I’m new to cgroup and block layer, recently I found a strange phenomenon in cgroup blkio stat as blow. I setup a blkio cgroup and wrote 1GB data in direct mode, but the stat indicated almost wrote 2.56GB, I tested several times in physical machine on cgroup v1 & v2 and both were same results, but interesting thing is when testing on VM(virtual machine) the stat is exactly the same as the data size had written. Could anyone give me a hint or explanation for this? testing info: ------------------------------------------------------------- $ uname -r 4.15.2 $ echo $$ 4242 $ cat /cgroup2/22/cgroup.procs 4242 13868 $ cat cgroup.controllers io memory $ df /mnt/sdb1 Filesystem 1K-blocks Used Available Use% Mounted on /dev/sdb1 209612800 18102292 191510508 9% /mnt/sdb1 $ lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT sdb 8:16 0 557.9G 0 disk ├─sdb2 8:18 0 357.9G 0 part └─sdb1 8:17 0 200G 0 part /mnt/sdb1 sdc 8:32 0 557.9G 0 disk ├─sdc2 8:34 0 100G 0 part ├─sdc3 8:35 0 100G 0 part ├─sdc1 8:33 0 100G 0 part └─sdc4 8:36 0 257.9G 0 part sda 8:0 0 557.9G 0 disk ├─sda2 8:2 0 542.2G 0 part / └─sda1 8:1 0 15.6G 0 part [SWAP] $ dd if=/dev/zero of=/mnt/sdb1/22/test bs=1M count=1024 oflag=direct 1024+0 records in 1024+0 records out 1073741824 bytes (1.1 GB) copied, 2.47852 s, 433 MB/s $ cat /cgroup2/22/io.stat 8:0 rbytes=1105920 wbytes=36864 rios=59 wios=4 8:16 rbytes=10330624 wbytes=2693799936 rios=102 wios=4105 Thanks, Chengguang. -- To unsubscribe from this list: send the line "unsubscribe cgroups" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
