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Bug 2052919

Summary: [DDF] Document the krb5kdc worker processes parameter and how to adjust it
Product: Red Hat Enterprise Linux 8 Reporter: Direct Docs Feedback <ddf-bot>
Component: DocumentationAssignee: Filip Hanzelka <fhanzelk>
Documentation sub component: DDF QA Contact:
Status: CLOSED CURRENTRELEASE Docs Contact:
Severity: unspecified    
Priority: high CC: elpereir, jvilicic, rhel-docs, tscherf
Version: 8.0Keywords: Documentation
Target Milestone: rcFlags: pm-rhel: mirror+
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Hardware: All   
OS: All   
Whiteboard:
Fixed In Version: Doc Type: If docs needed, set a value
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2022-03-01 22:39:11 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:

Description Direct Docs Feedback 2022-02-10 09:43:39 UTC
Based on a recent customer case I would suggest to add the following tuning parameter to this section:

/etc/sysconfig/krb5kdc:
KRB5KDC_ARGS="-w "

From 'man 8 krb5kdc':

"""
The  -w  numworkers  option tells the KDC to fork numworkers processes to listen to the KDC ports and process
       requests in parallel.  The top level KDC process (whose pid is recorded in the pid file if the -P  option  is
       also  given)  acts as a supervisor.  The supervisor will relay SIGHUP signals to the worker subprocesses, and
       will terminate the worker subprocess if the it is itself terminated or if any other worker process exits.
"""

Please note,  there is already code available that auto-detects the  number of online CPUs and then sets the number of krb5kdc worker threads dynamically.  It relies on
SC_NPROCESSORS_ONLN sysconf value. But I think it's useful to have this option documented for cases where the system configuration is changed after the initial setup. This can easily happen especially in virtual environments where you can easily add or remove the number of virtual CPUs based on your requirements.

Reported by: rhn-support-tscherf

https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8/html/tuning_performance_in_identity_management/assembly_adjusting-the-performance-of-the-kdc_tuning-performance-in-idm#annotations:2da352c6-8854-4260-a028-ab20bc95fd4c