Device Mapper Proxy (dmp) module with statistics

Device Mapper Proxy (dmp) is a kernel module for the Linux operating system that creates virtual block devices on top of existing devices using the device mapper framework. The module also monitors and provides statistics on the performed operations, which are accessible through the sysfs interface.

Remarks

I used Ubuntu 22.04.3 LTS with the 5.15.0-92-generic kernel for building and testing the module

Installation

Clone the repository:

git clone https://github.com/npanuhin/edu-dmp-stats-module

Building and Testing

To build and intially test the module, run run.sh. It will give a nice summary of the operations performed and will run a simple test to check the module's functionality.

sh ./run.sh

Click to see the output

=============================================== Updating the code ===============================================
Removing .Module.symvers.cmd
Removing .dmp.ko.cmd
Removing .dmp.mod.cmd
Removing .dmp.mod.o.cmd
Removing .dmp.o.cmd
Removing .modules.order.cmd
Removing Module.symvers
Removing dmp.ko
Removing dmp.mod
Removing dmp.mod.c
Removing dmp.mod.o
Removing dmp.o
Removing modules.order
Already up to date.

=============== Removing previously inserted module, zero device and device-mapper proxy device ===============

============================================== Building the module =============================================
make -C /lib/modules/5.15.0-92-generic/build M=/home/npanuhin/tools/edu-dm-proxy-stats-module modules
make[1]: Entering directory '/usr/src/linux-headers-5.15.0-92-generic'
  CC [M]  /home/npanuhin/tools/edu-dm-proxy-stats-module/dmp.o
  MODPOST /home/npanuhin/tools/edu-dm-proxy-stats-module/Module.symvers
  CC [M]  /home/npanuhin/tools/edu-dm-proxy-stats-module/dmp.mod.o
  LD [M]  /home/npanuhin/tools/edu-dm-proxy-stats-module/dmp.ko
  BTF [M] /home/npanuhin/tools/edu-dm-proxy-stats-module/dmp.ko
Skipping BTF generation for /home/npanuhin/tools/edu-dm-proxy-stats-module/dmp.ko due to unavailability of vmlinux
make[1]: Leaving directory '/usr/src/linux-headers-5.15.0-92-generic'

=============================================== Creating devices ==============================================
crw------- 1 root root 10, 236 фев  9 00:10 /dev/mapper/control
lrwxrwxrwx 1 root root       7 фев  9 00:17 /dev/mapper/zero1 -> ../dm-0
crw------- 1 root root 10, 236 фев  9 00:10 /dev/mapper/control
lrwxrwxrwx 1 root root       7 фев  9 00:17 /dev/mapper/dmp1 -> ../dm-1
lrwxrwxrwx 1 root root       7 фев  9 00:17 /dev/mapper/zero1 -> ../dm-0

============================================== Testing the module =============================================
1+0 records in
1+0 records out
4096 bytes (4,1 kB, 4,0 KiB) copied, 0,00151003 s, 2,7 MB/s
1+0 records in
1+0 records out
4096 bytes (4,1 kB, 4,0 KiB) copied, 0,000888471 s, 4,6 MB/s

=============================================== Module statistics =============================================
read:
  reqs: 2286
  avg size: 1004
write:
  reqs: 8
  avg size: 512
total:
  reqs: 2294
  avg size: 1003

Further Usage

• To reset the statistics, run:

   echo > /sys/module/dmp/stat/volumes

• To view the statistics, run:

   cat /sys/module/dmp/stat/volumes

  Click to see the sample output

   read:
     reqs: 83
     avg size: 1875
   write:
     reqs: 0
     avg size: 0
   total:
     reqs: 83
     avg size: 1875