Bug 256594 - AMD Ryzen CPU stutter (responsiveness lag)
Summary: AMD Ryzen CPU stutter (responsiveness lag)
Status: New
Alias: None
Product: Base System
Classification: Unclassified
Component: kern (show other bugs)
Version: 13.0-STABLE
Hardware: amd64 Any
: --- Affects Some People
Assignee: freebsd-bugs (Nobody)
Keywords: performance
Depends on:
Reported: 2021-06-14 08:52 UTC by Jack
Modified: 2021-06-18 14:06 UTC (History)
5 users (show)

See Also:


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Description Jack 2021-06-14 08:52:37 UTC
Using current CPU: AMD Ryzen 7 5800X 8-Core Processor              (3800.07-MHz K8-class CPU)

When running X on 13-STABLE, everything has a micro delay. When playing videos, the video keeps stuttering and audio periodically skips. Dragging things are not smooth, screen keeps stalling. An exact description of the problem was reported on the mailing list

Setting kern.sched.steal_thresh=0 made the problem go away completely.

Anything higher than 0 produces noticeable stuttering and delays in visuals and audio.
Comment 1 Mark Linimon freebsd_committer freebsd_triage 2021-06-14 12:11:19 UTC
^Triage: I am not really sure how to assign this.  But in the mean time, give it a little fuller Summary, and put the "performance" Keyword on.
Comment 2 crest 2021-06-14 13:21:53 UTC
I can confirm this observation on a R9 3950X with 32GB, booted from an NVMe SSD and a RTX 3090 even such "simple" things as scrolling in Chromium result in painful stuttering and glaring tearing with i3 as window manager.
Comment 3 Alan Somers freebsd_committer 2021-06-18 14:06:15 UTC
This was recently discussed on freebsd-current.  CCing some of the folks from that thread.