Bug 1886738 - High number of context switches caused by VDO kernel threads while vdo volume is unused or idle
Summary: High number of context switches caused by VDO kernel threads while vdo volume...
Alias: None
Product: Red Hat Enterprise Linux 8
Classification: Red Hat
Component: kmod-kvdo
Version: 8.4
Hardware: All
OS: Linux
Target Milestone: rc
: 8.0
Assignee: Ken Raeburn
QA Contact: Filip Suba
Depends On:
TreeView+ depends on / blocked
Reported: 2020-10-09 09:37 UTC by Nikolay Kichukov
Modified: 2021-11-10 06:37 UTC (History)
7 users (show)

Fixed In Version:
Doc Type: If docs needed, set a value
Doc Text:
Clone Of:
Last Closed: 2021-11-09 19:28:28 UTC
Type: Bug
Target Upstream Version:

Attachments (Terms of Use)

System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHBA-2021:4359 0 None None None 2021-11-09 19:28:38 UTC

Description Nikolay Kichukov 2020-10-09 09:37:42 UTC
Hi team,

This report is somehow related to and can be considered a continuation of: 

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

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:


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

Thank you,

Comment 1 Nikolay Kichukov 2021-02-22 19:48:41 UTC
Hi folks,
any progress update with this?

Comment 2 Ken Raeburn 2021-03-09 19:41:46 UTC
(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.

Comment 6 Filip Suba 2021-08-16 13:08:10 UTC
Verified with kmod-kvdo-

Comment 9 errata-xmlrpc 2021-11-09 19:28:28 UTC
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.


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