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Maniphest T8781

vyos-netlinkd high CPU usage with lots of route updates
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Description

Hi,

I've found this bug while updating some routers within AS203528 network from 2025.09.17-0018-rolling to 2026.05.05-0039-rolling

vyos-netlinkd is now using a lot of CPU, sometimes about half a core, sometimes a full CPU core.
This is only seen in routers that have full BGP tables, in my environment routers receive 3xfull IPv6 BGP tables from 4 different RRs, so there are a lot of route updates going on.

from ps aux:

root        4019 35.0  1.0  76004 65368 ?        Ss   May05 333:35 /usr/bin/python3 -u /usr/libexec/vyos/services/vyos-netlinkd

I had a locally-running LLM+harness inspect the strace of that process for me and create a patch (which when applied does seem to work just fine on my router and lowered the CPU usage back to normal). It's literal AI slop though. I've attached below the LLM-generated investigation + patch.

I still have routers running on old / new version so I could test whatever is needed or provide strace outputs.

vyos-netlinkd-cpu-fix.patch4 KBDownload

vyos-bug-report.md2 KBDownload

Details

Version
2026.05.05-0039-rolling
Is it a breaking change?
Unspecified (possibly destroys the router)
Issue type
Bug (incorrect behavior)
Forum thread
https://forum.vyos.io/t/vyos-netlinkd-high-cpu-usage/17442

Related Objects

Event Timeline

fabrizziop created this task.May 6 2026, 11:56 AM
fabrizziop created this object in space S1 VyOS Public.
fabrizziop created this object with edit policy "Custom Policy".
pasik subscribed.May 6 2026, 5:24 PM
Viacheslav assigned this task to c-po.May 11 2026, 3:39 PM
Viacheslav triaged this task as High priority.
c-po set Forum thread to https://forum.vyos.io/t/vyos-netlinkd-high-cpu-usage/17442.May 14 2026, 12:17 PM
c-po added a comment.May 14 2026, 2:38 PM

@fabrizziop thank you for the patch. I would like to partly reuse it and add you as author. Your commit is authored by Fabrizio <fabrizzio@example.com> - is this what you wan't or what Name/Familyname/mail should I include.

fabrizziop added a comment.May 14 2026, 2:44 PM
In T8781#264420, @c-po wrote:

@fabrizziop thank you for the patch. I would like to partly reuse it and add you as author. Your commit is authored by Fabrizio <fabrizzio@example.com> - is this what you wan't or what Name/Familyname/mail should I include.

Hey!, please use Fabrizzio Petrucci - fabrizziopm@compumundohipermegared.one

Thanks!.

c-po added a comment.May 14 2026, 3:53 PM

@fabrizziop https://github.com/vyos/vyos-1x/pull/5199 please sign the CLA by replying: I have read the CLA Document and I hereby sign the CLA as I put you in as author of the commit

c-po added a comment.EditedMay 14 2026, 4:02 PM

commit lock optimisation is in https://github.com/vyos/vyos-1x/pull/5200 which we might backport to 1.5.1 earlier then vyos-netlinkd

Apachez subscribed.May 14 2026, 6:47 PM
Viacheslav changed the task status from Open to Needs testing.May 15 2026, 2:25 PM
Restricted Repository Identity mentioned this in rVYOSONEX08542c03c0d1: vyos-netlinkd: T8781: do not call commit_in_progress() for EVERY netlink….May 15 2026, 2:26 PM
c-po mentioned this in rVYOSONEX02a7f2ab7130: vyos.commit: T8781: move from O(n) to O(1) for commit_in_progress() checks.May 18 2026, 3:03 PM
c-po mentioned this in rVYOSONEXabd22ba6c385: vyos-netlinkd: T8781: use faster commit_in_progress2 with order O(1).
Restricted Repository Identity mentioned this in rVYOSONEXedccb2fc9116: Merge pull request #5200 from c-po/commit-in-progress.May 18 2026, 3:03 PM
c-po added a comment.May 18 2026, 3:28 PM

https://github.com/vyos/vyos-1x/pull/5207

Restricted Repository Identity mentioned this in rVYOSONEX51ab39e51bb9: vyos-netlinkd: T8781: try IPRoute.bind() RTNL subscription first (#5207).May 18 2026, 3:35 PM
c-po added a comment.May 18 2026, 3:41 PM

Rolling release starting from 2026-05-19 will have all necessary fixes inside. I am keen to get the results.

fabrizziop added a comment.May 18 2026, 3:48 PM

I have upgraded all my routers already to 2026-05-16 rolling and the CPU usage problem was fixed.

Screenshot_20260518-174534.png (1×1 px, 290 KB)

pasik added a comment.May 19 2026, 6:59 AM

vyos nightly 2026.05.19-0047-rolling seems to be now available.

@fabrizziop please also test with that version, which has the latest related changes.

fabrizziop added a comment.May 19 2026, 7:25 AM

@pasik I've just tested with 2026.05.19-0047-rolling - it is working fine as well, thanks!.

c-po closed this task as Resolved.Thu, May 21, 6:22 AM
cr0ntab mentioned this in T8950: vyos-netlinkd: DHCP restart on every RTM_NEWLINK(UP) without tracking previous state.Sun, May 31, 8:12 PM