Note: This bug is displayed in read-only format because the product is no longer active in Red Hat Bugzilla.

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.

Hi team,

This report is somehow related to and can be considered a continuation of: 
https://bugzilla.redhat.com/show_bug.cgi?id=1870660

We would be looking to minimize the number of context switches from the VDO threads this time.

Current state: starting VDO volumes that are not in use on an idle system increases the number of context switches with around 8000 context switches / second.

On an idle physical system with 4 CPUs running kernel 5.8.14 and kvdo-corp 6.2.4.14:

VDO devices are not started: 90 context switches / second
VDO devices(2 devices) are started and not used: 8000 context switches / second

The threads that consume the CPU seem to be:


 [kvdo2:packerQ]
 [kvdo2:ackQ]
 [kvdo2:cpuQ0]
 [kvdo2:cpuQ1]
 [kvdo3:dedupeQ]
 [kvdo3:journalQ]
 [kvdo3:hashQ0]
 [kvdo3:bioQ0]
 [kvdo3:bioQ1]
 [kvdo3:bioQ2]
 [kvdo3:bioQ3]
 [kvdo3:cpuQ0]
 [kvdo3:cpuQ1]

In an ideal world, having started an idling VDO volume should not increase the number of context switches on the system.

Thank you,
-Nikolay

Hi folks,
any progress update with this?

(In reply to Nikolay Kichukov from comment #1)
> Hi folks,
> any progress update with this?

Sorry, Nikolay, not so far. I've had another work item ahead of it in my queue... I'll be looking into it this week though.

Verified with kmod-kvdo-6.2.5.72-79.el8

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory (kmod-kvdo bug fix and enhancement update), and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2021:4359