1. Administrator's Guide
  2. Troubleshooting
  3. Linux 7.3 and 7.6 Performance Issues

Linux 7.3 and 7.6 Performance Issues

Under Linux 7.3 and 7.6, significant ACSLS performance slowdown conditions may occur. These conditions are traced to missing host entries and the use of the SSSD service.

Slow resolution of UIDs, groups, automounts, permissions, and related details can have wide-ranging impacts. Many applications, including ACSLS, use the su command, which requires resolution of system user details prior to proceeding.

Missing Host Entry

Make sure that you do not have a missing host entry in your /etc/hosts file. Include both the fully qualified host name and shortened version. For example: 

[root@mycomputer ~]# cat /etc/hosts
10.0.0.0      mycomputer.us.domain-name.com     mycomputer

SSSD

Use of the Linux System Security Services Daemon (SSSD) service can impact ACSLS performance, causing numerous types of slowdown conditions. These conditions revolve around refreshing of a cache and re-walking trees of user names, groups, permissions, and so on.

If you encounter a slowdown condition, use the following guidelines to determine whether the condition is related to your use of SSSD:

Diagnosis 1

  1. Verfiy that the machine is responding slowly to any su command.
  2. Check the /etc/nsswitch.conf file for occurrences of "sssd". If you do not find occurrences of "sssd" then proceed with Diagnosis 2.
  3. For diagnostic purposes, remove any occurrences of "sssd". No restart required.
  4. Test the su command again several times, to varying users. If response time is improved, then the SSSD service is the root cause of your slowdown condition.

Diagnosis 2

If there are no occurrences of "sssd" in the /etc/nsswitch.conf file, SSSD can still cause slow performance.

  1. As root, enter the following command to display the status of the SSSD service:
    systemctl status sssd.service
  2. If the service is active, enter the following command to turn it off:
    systemctl stop sssd.service
  3. Enter the following command to disable the SSSD service:
    systemctl disable sssd.service
  4. Test the su command again several times, to varying users. If response time is improved, then the SSSD service is the root cause of your slowdown condition.