update

28_checking_resources/README.md

@@ -3,6 +3,7 @@ Demonstrate how to use various commands to verify resource usage in the OS.
 
 
 TODO:
+* cgroups
 * Open sockets
 * Free memory 
 * File handles
@@ -12,10 +13,33 @@ TODO:
 * debugfs
 https://github.com/raboof/nethogs
 
+
+```sh
+# booted with
+cat /proc/cmdline 
+
+# built with
+cat /boot/config-5.8.0-49-generic | grep CGROUP
+
+# global limits
+systemctl show     
+```
+
 ## Check limits
 ```sh
-ulimit -a
+# limits inside a container
+docker run -it ubuntu:20.04 /bin/bash -c "ulimit -a" 
+
+# limits on host
+ulimit -a 
+
+# limits for current pid
+cat /proc/$$/limits 
+
+# show global config
+systemctl show    
 ```
+
 ## Disk
 
 ```sh

34_checking_resources/CGROUPS.md

@@ -1,30 +1,53 @@
-https://www.linuxjournal.com/content/everything-you-need-know-about-linux-containers-part-i-linux-control-groups-and-process
-
-https://www.linuxjournal.com/content/everything-you-need-know-about-linux-containers-part-ii-working-linux-containers-lxc
+# README
+Demonstrate how to work with cgroups
 
+## cgroups 
+```sh
+# man pages
+man cgroups
 
-SSH in a cgroup
-https://unix.stackexchange.com/questions/209199/how-to-ensure-ssh-via-cgroups-on-centos
-
-https://unix.stackexchange.com/questions/56538/controlling-priority-of-applications-using-cgroups
-
-cgroupsv2
-https://unix.stackexchange.com/questions/471476/how-do-i-check-cgroup-v2-is-installed-on-my-machine
+# list filesystems and look at cgroups
+cat /proc/filesystems  
 
-## Limits
-docker run -it ubuntu:20.04 /bin/bash -c "ulimit -a" 
+# see where they a virtually mounted
+mount
+```
 
-ulimit -a 
+## Install tooling
+```sh
+# install tooling
+sudo apt install cgroup-tools        
 
-cat /proc/$$/limits 
+# list cgroup tools
+dpkg -L cgroup-tools | grep bin        
 
-## Cgroups 
-```sh
-cat /proc/filesystems  
-mount
 ```
 
+## Walk the filesystem
 ```sh
+# cgroups v1
 ls /sys/fs/cgroup/
+
+# cgroups v2
+ls /sys/fs/cgroup/unified     
 ```
 
+
+## Resources
+https://medium.com/nttlabs/cgroup-v2-596d035be4d7
+
+
+https://opensource.com/article/20/10/cgroups
+
+https://www.linuxjournal.com/content/everything-you-need-know-about-linux-containers-part-i-linux-control-groups-and-process
+
+https://www.linuxjournal.com/content/everything-you-need-know-about-linux-containers-part-ii-working-linux-containers-lxc
+
+
+SSH in a cgroup
+https://unix.stackexchange.com/questions/209199/how-to-ensure-ssh-via-cgroups-on-centos
+
+https://unix.stackexchange.com/questions/56538/controlling-priority-of-applications-using-cgroups
+
+cgroupsv2
+https://unix.stackexchange.com/questions/471476/how-do-i-check-cgroup-v2-is-installed-on-my-machine