blktrace block device tool
Introduction
blktrace is block layer IO tracing mechanism while provides detailed information about request queue operations up to user space
Install on RedHat/CentOS/OEL
Download epel-release-6-8.noarch.rpm and install then using below command.
#yum install blktrace
Setup
#mount -t debugfs debugfs /sys/kernel/debug
Add an entry into /etc/fstab, and have it done automatically at each boot.
debug /sys/kernel/debug debugfs debugfs 0 0
blktrace – live
[root@FSS-H13-102 ~]# blktrace -d /dev/ram0 -o – | blkparse -i –
1,0 4 1 0.000000000 6516 Q R 1 + 1 [(null)]
1,0 2 1 1266874889.709410185 6516 Q R 0 + 1 [bksc_exec]
1,0 2 2 12.002501106 6516 Q R 0 + 1 [bksc_exec]
1,0 0 1 12.002557330 6516 Q R 1 + 1 [bksc_exec]
1,0 1 1 13.434488103 6558 Q R 20480 + 32 [kdownstream/1]
1,0 1 2 13.434928252 6558 Q R 942072 + 8 [kdownstream/1]
1,0 1 3 13.435318671 6558 Q R 20480 + 32 [kdownstream/1]
1,0 1 4 13.435792065 6558 Q R 20512 + 64 [kdownstream/1]
