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  1. RHEL
  2. RHEL-5142

[RFE] Disable Transparent Huge Pages when using large caches. [rhel-9.4.0]

    • 389-ds-base-2.4.5-2.el9
    • Major
    • sst_idm_ds
    • ssg_idm
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    • Enhancement
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      .Transparent Huge Pages are now disabled by default for the `ns-slapd` process

      When large database caches are used, Transparent Huge Pages (THP) can have a negative effect on Directory Server performance under heavy load, for example, high memory footprint, high CPU usage and latency spikes. With this enhancement, a new `THP_DISABLE=1` configuration option was added to the `/usr/lib/systemd/system/dirsrv@.service.d/custom.conf` drop-in configuration file for the `dirsrv` `systemd` unit to disable THP for the `ns-slapd` process.

      In addition, the Directory Server health check tool now detects the THP settings. If you enabled THP system-wide and for the Directory Server instance, the health check tool informs you about the enabled THP and prints recommendations on how to disable them.

      //For more details about the health check tool, refer to link:https://access.redhat.com/documentation/en-us/red_hat_directory_server/12/html/monitoring_server_and_database_activity/using-the-health-check-to-identify-problems_monitoring-server-and-database-activities[Using the health check to identify problems]
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      .Transparent Huge Pages are now disabled by default for the `ns-slapd` process When large database caches are used, Transparent Huge Pages (THP) can have a negative effect on Directory Server performance under heavy load, for example, high memory footprint, high CPU usage and latency spikes. With this enhancement, a new `THP_DISABLE=1` configuration option was added to the `/usr/lib/systemd/system/dirsrv@.service.d/custom.conf` drop-in configuration file for the `dirsrv` `systemd` unit to disable THP for the `ns-slapd` process. In addition, the Directory Server health check tool now detects the THP settings. If you enabled THP system-wide and for the Directory Server instance, the health check tool informs you about the enabled THP and prints recommendations on how to disable them. //For more details about the health check tool, refer to link: https://access.redhat.com/documentation/en-us/red_hat_directory_server/12/html/monitoring_server_and_database_activity/using-the-health-check-to-identify-problems_monitoring-server-and-database-activities [Using the health check to identify problems]
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      Description of problem:
      As described in bug 2068120, THP can have negative effects on RHDS performance.
      This seems to happen with large caches.
      Some customers are getting uncontrolled memory usage while others are seeing high CPU consumption.
      It would make sense to either disable THP for RHDS or at least add some messages in the errors logs.
      RHDS healthcheck tool should also report when THP is enabled on the system.

      Version-Release number of selected component (if applicable):
      This is impacting all RHDS 11 and 12 versions.

      How reproducible:
      At customer sites.

      Steps to Reproduce:
      1. Configure large caches ( > 50 GB )
      2. Check memory and CPU usage when RHDS is under heavy load
      3. Disable THP ==> RHDS uses less memory and CPU

      Actual results:
      High memory and CPU usage.

      Expected results:
      Controlled memory and CPU usage.

      Additional info:
      https://access.redhat.com/solutions/3799821

            vashirov@redhat.com Viktor Ashirov
            rhn-support-tmihinto Têko Mihinto
            Viktor Ashirov Viktor Ashirov
            Barbora Simonova Barbora Simonova
            Evgenia Martyniuk Evgenia Martyniuk
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              Created:
              Updated:
              Resolved: