[Bug 2146027] Re: Virtual Machine Performance Impacted

** Tags added: kernel-daily-bug

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Title:
Virtual Machine Performance Impacted

Status in linux package in Ubuntu:
New

Bug description:
Here's an ODD 'feature' of kernel 6.8.0-106 I'm running into:

OS: Kubuntu 24.04.4 (LTS)
KDE Plasma: 5.27.12
KDE Frameworks: 5.115.0
Qt Version: 5.15.13
Kernel Version: 6.8.0-106-generic (64-bit)
Graphics Platform: X11
Processors: 8 × AMD FX(tm)-8320 Eight-Core Processor
Memory: 15.7 GiB of RAM
Graphics Processor: PITCAIRN
Motherboard: Gigabyte Technology Co., Ltd.

linux-image-6.8.0-106-generic:
Installed: 6.8.0-106.106
Candidate: 6.8.0-106.106
Version table:
*** 6.8.0-106.106 500
500 http://us.archive.ubuntu.com/ubuntu noble-updates/main amd64 Packages
500 http://us.archive.ubuntu.com/ubuntu noble-security/main amd64 Packages
100 /var/lib/dpkg/status

I run VMware Workstation 17 Pro (17.6.4 build-24832109) and have used "Slices"
to Assign Core Affinity for the Host OS, User Apps and VMs:

System Slice = SMP Cores 0-3
User Slice = SMP Cores 4-7

This is done in order to maximize the performance of the VMs (CAElinux, Kubuntu,
MS Windows 10/11 Pro, etc.) by modding the *.vmx files to map the VMs onto only
the upper 4-cores of the processor. It works, Rock Solid (on -101).

When I run on -106 the VMs get REAL 'Choppy' and begin seeing audio breakup and
are no longer capable of maximum "Core Utilization" on the upper 4-cores.

I've observed the above in both OCCT and applications with 3D graphics and audio
being run in both of the Windows VMs (I no longer run MS on Bare Metal).

I have attached System Monitor History Screen Captures that illustrate
the impact.

ProblemType: Bug
DistroRelease: Ubuntu 24.04
Package: linux-image-6.8.0-106-generic 6.8.0-106.106
ProcVersionSignature: Ubuntu 6.8.0-106.106-generic 6.8.12
Uname: Linux 6.8.0-106-generic x86_64
ApportVersion: 2.28.1-0ubuntu3.8
Architecture: amd64
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC0: tamaster 3442 F.... wireplumber
/dev/snd/controlC1: tamaster 3442 F.... wireplumber
/dev/snd/seq: tamaster 3438 F.... pipewire
CasperMD5CheckResult: unknown
CurrentDesktop: KDE
Date: Tue Mar 24 11:56:40 2026
InstallationDate: Installed on 2020-10-10 (1991 days ago)
InstallationMedia: Kubuntu 20.04.1 LTS "Focal Fossa" - Release amd64 (20200731)
MachineType: Gigabyte Technology Co., Ltd. To be filled by O.E.M.
ProcFB: 0 radeondrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-6.8.0-106-generic root=UUID=4918d7fa-4d57-4dc6-a309-1e93b981ad68 ro iommu=soft quiet splash transparent_hugepage=never preempt=full nohz_full=all threadirqs vt.handoff=7
PulseList: Error: command ['pacmd', 'list'] failed with exit code 1: No PulseAudio daemon running, or not running as session daemon.
RelatedPackageVersions:
linux-restricted-modules-6.8.0-106-generic N/A
linux-backports-modules-6.8.0-106-generic N/A
linux-firmware 20240318.git3b128b60-0ubuntu2.25
RfKill:

SourcePackage: linux
UpgradeStatus: Upgraded to noble on 2024-08-30 (571 days ago)
dmi.bios.date: 05/28/2015
dmi.bios.release: 4.6
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: F3
dmi.board.asset.tag: To be filled by O.E.M.
dmi.board.name: 990FXA-UD3
dmi.board.vendor: Gigabyte Technology Co., Ltd.
dmi.board.version: x.x
dmi.chassis.asset.tag: To Be Filled By O.E.M.
dmi.chassis.type: 3
dmi.chassis.vendor: Gigabyte Technology Co., Ltd.
dmi.chassis.version: To Be Filled By O.E.M.
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrF3:bd05/28/2015:br4.6:svnGigabyteTechnologyCo.,Ltd.:pnTobefilledbyO.E.M.:pvrTobefilledbyO.E.M.:rvnGigabyteTechnologyCo.,Ltd.:rn990FXA-UD3:rvrx.x:cvnGigabyteTechnologyCo.,Ltd.:ct3:cvrToBeFilledByO.E.M.:skuTobefilledbyO.E.M.:
dmi.product.family: To be filled by O.E.M.
dmi.product.name: To be filled by O.E.M.
dmi.product.sku: To be filled by O.E.M.
dmi.product.version: To be filled by O.E.M.
dmi.sys.vendor: Gigabyte Technology Co., Ltd.

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