dmp

a target for device mapper that catch all requests and create stat

To creat a .ko file use

make

After you to install module

insmod /path/to/module/dmp.ko

Create a test block device

dmsetup create zero1 --table "0 20000 zero"

Check if created

ls -al /dev/mapper/*

Then create a dmp device

dmsetup create dmp1 --table "0 $size dmp /dev/mapper/zero1

Requests for read/write

# dd if=/dev/random of=/dev/mapper/dmp1 bs=4k count=1 0+1 records in 0+1 records out 115 bytes copied, 0.000241373 s, 476 kB/s dd of=/dev/null if=/dev/mapper/dmp1 bs=4k count=1 1+0 records in 1+0 records out 4096 bytes (4.1 kB, 4.0 KiB) copied, 0.000166921 s, 24.5 MB/s

Statistics

cat /sys/module/dmp/stat/volumes read: reqs: 100 avg size: 4096 write: reqs: 10 avg size: 4096 total: reqs: 110 avg size: 4096