[Bug 2076361] Re: Lenovo X12 Detachable Gen 2 unresponsive under light load

This bug is awaiting verification that the linux-xilinx/6.8.0-1009.10
kernel in -proposed solves the problem. Please test the kernel and
update this bug with the results. If the problem is solved, change the
tag 'verification-needed-noble-linux-xilinx' to 'verification-done-
noble-linux-xilinx'. If the problem still exists, change the tag
'verification-needed-noble-linux-xilinx' to 'verification-failed-noble-
linux-xilinx'.


If verification is not done by 5 working days from today, this fix will
be dropped from the source code, and this bug will be closed.


See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how
to enable and use -proposed. Thank you!


** Tags added: kernel-spammed-noble-linux-xilinx-v2 verification-needed-noble-linux-xilinx

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Title:
Lenovo X12 Detachable Gen 2 unresponsive under light load

Status in linux package in Ubuntu:
New
Status in linux-oem-6.8 package in Ubuntu:
New
Status in linux-signed package in Ubuntu:
Invalid
Status in linux-signed-lowlatency package in Ubuntu:
Invalid
Status in linux source package in Noble:
Fix Committed
Status in linux-oem-6.8 source package in Noble:
Fix Released
Status in linux-signed source package in Noble:
Invalid
Status in linux-signed-lowlatency source package in Noble:
Invalid

Bug description:
SRU Justification:
==============

[Impact]
To encode some video files with ffmpeg, and the system becomes completely
unresponsive for as long as the process executes.

[Fix]
Enable Wa_14019159160 and Wa_16019325821 for MTL.

[Test]
Tested on hardware, the system works fine when run the same script to
encode.

[Where problems could occur]
It may break intel i915 driver.
=========================

I've been using a Lenovo X12 Detachable Gen 2 model from 2024 [1] to
encode some video files with ffmpeg, and the system becomes completely
unresponsive for as long as the process executes. Although small, this
is a pretty good device hardware wise, and while executing the system
has plenty of RAM (32GB total, 10GB+ left), almost all CPUs are idle,
no IO wait.

[1] Intel Core Ultra 164U variant at:
https://psref.lenovo.com/syspool/Sys/PDF/Think_Tablets/ThinkPad_X12_Detachable_Gen_2/ThinkPad_X12_Detachable_Gen_2_Spec.pdf

Things I've tried:

1) Lowering the priority of ffmpeg with renice
2) Lowering the priority of ffmpeg with ionice
3) Using a single thread in ffmpeg
4) Switching to the lowlatency kernel, with all recommended fiddling
5) Switching to the OEM kernel (6.8.0-1010-oem)

Nothing even touches the complete lack of responsiveness. The system
becomes so unresponsive that when typing nothing shows up, and then
characters show repeated as long sequences all at once.

In addition to the attached information, some details about the moment
the problem happens:

top - 16:27:49 up 3:26, 1 user, load average: 1.13, 0.70, 0.68
Tasks: 397 total, 1 running, 396 sleeping, 0 stopped, 0 zombie
%Cpu0 : 2.7 us, 0.0 sy, 0.0 ni, 56.3 id, 41.0 wa, 0.0 hi, 0.0 si, 0.0 st
%Cpu1 : 3.3 us, 0.3 sy, 0.0 ni, 96.4 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st
%Cpu2 : 3.0 us, 0.0 sy, 0.0 ni, 97.0 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st
%Cpu3 : 0.7 us, 1.0 sy, 6.3 ni, 2.7 id, 89.3 wa, 0.0 hi, 0.0 si, 0.0 st
%Cpu4 : 3.7 us, 0.0 sy, 0.0 ni, 96.3 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st
%Cpu5 : 4.0 us, 0.3 sy, 0.0 ni, 95.7 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st
%Cpu6 : 3.3 us, 0.0 sy, 0.0 ni, 96.3 id, 0.3 wa, 0.0 hi, 0.0 si, 0.0 st
%Cpu7 : 3.7 us, 0.0 sy, 0.0 ni, 96.3 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st
%Cpu8 : 4.3 us, 0.0 sy, 0.0 ni, 95.7 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st
%Cpu9 : 3.7 us, 0.0 sy, 0.0 ni, 96.3 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st
%Cpu10 : 4.0 us, 0.0 sy, 0.0 ni, 96.0 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st
%Cpu11 : 3.7 us, 0.0 sy, 0.0 ni, 96.3 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st
%Cpu12 : 3.0 us, 0.3 sy, 0.0 ni, 96.7 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st
%Cpu13 : 4.0 us, 0.0 sy, 0.0 ni, 96.0 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st
MiB Mem : 31537.6 total, 9596.6 free, 9784.3 used, 15292.1 buff/cache
MiB Swap: 8192.0 total, 8192.0 free, 0.0 used. 21753.3 avail Mem

Linux 6.8.0-39-lowlatency (x12) 08/08/2024 _x86_64_
(14 CPU)

avg-cpu: %user %nice %system %iowait %steal %idle
           2.87 0.04 0.26 7.48 0.00 89.35

It may also be worth mentioning, the ffmpeg process is using hardware
encoding/decoding.

Thanks for any help on this.

ProblemType: Bug
DistroRelease: Ubuntu 24.04
Package: linux-image-6.8.0-39-lowlatency 6.8.0-39.39.1
ProcVersionSignature: Ubuntu 6.8.0-39.39.1-lowlatency 6.8.8
Uname: Linux 6.8.0-39-lowlatency x86_64
ApportVersion: 2.28.1-0ubuntu3
Architecture: amd64
CasperMD5CheckResult: pass
CurrentDesktop: ubuntu:GNOME
Date: Thu Aug 8 17:23:32 2024
InstallationDate: Installed on 2024-06-25 (44 days ago)
InstallationMedia: Ubuntu 24.04 LTS "Noble Numbat" - Release amd64 (20240424)
SourcePackage: linux-signed-lowlatency
UpgradeStatus: No upgrade log present (probably fresh install)

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