Configure cgroups using cgconfig

You can use the cgconfig service installed with libcgroup to create cgroups on Linux systems not running systemd.

To configure cgroups for workload management using cgconfig:

1. Check that /sys/fs is mounted. If it is not mounted, mount the tmpfs in-memory filesystem under /sys/fs/cgroup as follows:

   sudo mount -t tmpfs -o size=10M tmpfs /sys/fs
   

   Note: Splunk Enterprise examines the /proc/mounts file to determine whether your Linux machine can support workload management.
2. Create the cgconfig.conf file under /etc and add the following contents:

   #  Copyright IBM Corporation. 2007
   #
   #  Authors: Balbir Singh <balbir@linux.vnet.ibm.com>
   #  This program is free software; you can redistribute it and/or modify it
   #  under the terms of version 2.1 of the GNU Lesser General Public License
   #  as published by the Free Software Foundation.
   #
   #  This program is distributed in the hope that it would be useful, but
   #  WITHOUT ANY WARRANTY; without even the implied warranty of
   #  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   #
   # See man cgconfig.conf for further details.
   #
   # By default, mount all controllers to /cgroup/<controller>
    
   mount {
       cpuset  = /sys/fs/cgroup/cpuset;
       cpu =     /sys/fs/cgroup/cpu;
       cpuacct = /sys/fs/cgroup/cpuacct;
       memory  = /sys/fs/cgroup/memory;
       devices = /sys/fs/cgroup/devices;
       freezer = /sys/fs/cgroup/freezer;
       net_cls = /sys/fs/cgroup/net_cls;
       blkio   = /sys/fs/cgroup/blkio;
   }
    
   group splunk {
       perm {
            admin {
                uid = "splunk";
                gid = "splunk";
            }
            task {
                uid = "splunk";
                gid = "splunk";
            }
        }
       cpu {
            cpu.shares = "2048";
           }
       memory {
            memory.limit_in_bytes = "3G";
              }
   }
   

3. Restart the cgconfig service.

   # service cgconfig restart
   Stopping cgconfig service:                                 [  OK  ]
   Starting cgconfig service:                                 [  OK  ]
   

   This creates the splunk cgroup.

   Note: The cgroup name must match the value of workload_pool_base_dir_name defined in workload_pools.conf The default value is splunk.

Configure cgroups using filesystem operations

To configure cgroups, the Linux admin, logged in as root user, must create the cgroups and assign the splunk user permissions to manage the cgroups, as follows:

1. In the workload_pools.conf. file, set workload_pool_base_dir_name to the root cgroup to be used by splunk. For example:

   [general]
   workload_pool_base_dir_name = splunk
   

   Or, send a POST request:

   workloads/config/set-base-dirname -workload_pool_base_dir_name <base_dir_name>
   

   For endpoint details, see workloads/config/set-base-dirname in the Splunk Enterprise REST API Reference Manual.

2. Create cpu and memory cgroups:

   sudo mkdir /sys/fs/cgroup/cpu/<workload_pool_base_dir_name>
   sudo mkdir /sys/fs/cgroup/memory/<workload_pool_base_dir_name>
   

3. Assign the splunk user permissions to manage the respective cgroups:

   sudo chown -R ${USER} /sys/fs/cgroup/cpu/<workload_pool_base_dir_name>
   sudo chown -R ${USER} /sys/fs/cgroup/memory/<workload_pool_base_dir_name>
   

   Note: If you have specified a user as SPLUNK_OS_USER in splunk-launch.conf, you must specify the same user as {USER} in the command. For more information see splunk-launch.conf in the Splunk Enterprise ''Admin Manual''.
4. Assign CPU shares for splunk cgroup:

   cd /sys/fs/cgroup/cpu/splunk
   echo 2048 > cpu.shares
   

5. Assign physical memory for the splunk cgroup:

   cd /sys/fs/cgroup/memory/splunk/
   echo 14G > memory.limit_in_bytes