RHEL Engineering is moving the tracking of its product development work on RHEL 6 through RHEL 9 to Red Hat Jira (issues.redhat.com). If you're a Red Hat customer, please continue to file support cases via the Red Hat customer portal. If you're not, please head to the "RHEL project" in Red Hat Jira and file new tickets here. Individual Bugzilla bugs in the statuses "NEW", "ASSIGNED", and "POST" are being migrated throughout September 2023. Bugs of Red Hat partners with an assigned Engineering Partner Manager (EPM) are migrated in late September as per pre-agreed dates. Bugs against components "kernel", "kernel-rt", and "kpatch" are only migrated if still in "NEW" or "ASSIGNED". If you cannot log in to RH Jira, please consult article #7032570. That failing, please send an e-mail to the RH Jira admins at rh-issues@redhat.com to troubleshoot your issue as a user management inquiry. The email creates a ServiceNow ticket with Red Hat. Individual Bugzilla bugs that are migrated will be moved to status "CLOSED", resolution "MIGRATED", and set with "MigratedToJIRA" in "Keywords". The link to the successor Jira issue will be found under "Links", have a little "two-footprint" icon next to it, and direct you to the "RHEL project" in Red Hat Jira (issue links are of type "https://issues.redhat.com/browse/RHEL-XXXX", where "X" is a digit). This same link will be available in a blue banner at the top of the page informing you that that bug has been migrated.

The RHEL real-time kernel is disabling nohz by default since kernel 3.10.0-320.rt56.196.el7 (bug 1206356), so we need to pass "nohz=on" in the host and guest profiles in order to enable it back.

Note that passing nozh_full= is not enough, we have to pass nohz_full= *and* nohz=on.

Fixed trivially upstream by the following commit:
https://git.fedorahosted.org/cgit/tuned.git/commit/?id=9aeb585a636a5987cb5053317f4d9bb83d27f3fa

I will create nicer fix once the feature from bug 1274464 is ready.

Thanks Jaroslav.

There's a discussion downstream about enabling nohz automagically when the kernel sees nohz_full= in the command-line. If this fix is implemented, then we don't have to rush with this on downstream (although it doesn't hurt having, in fact I think it's a good idea to have it because KVM-RT do depend on this feature).

Ah, Luiz beat me to it. I believe we'll have the nohz fix in 7.2 GA, presuming everything goes as planned. The fix is to to enable nohz if we see nohz_full while parsing/processing the boot command line. Bz for that one is 1274519.

The RHEL RT kernel got this issue fixed by enabling nohz when the kernel sees nohz_full= in the command-line (bug 1276071), so we don't need this fix anymore.

Jarda, sorry for making you fix this in upstream. You could revert the fix, as it's probably unusual to have nohz disabled by default. Or, you could leave it this way as it doesn't make any difference.