Comment 0 for bug 2076361

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) Switching to the lowlatency kernel, with all recommended fiddling
4) Using a single thread in ffmpeg

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)