On Wed, Jun 18, 2025 at 12:50 PM Heinrich Schuchardt < 2112...@bugs.launchpad.net> wrote:
> If I run the dual core inner VM via `taskset 0x03 qemu-system-riscv64 > ...`, the amd64 cores are released while the inner VM idles. But once > the inner VM is stopped the amd64 CPU consumption sticks at 2 CPUs. > > `mpstat -P ALL` provides this output > (https://paste.ubuntu.com/p/5ZDbDqJ86g/): > > > 07:38:56 PM CPU %usr %nice %sys %iowait %irq %soft > %steal %guest %gnice %idle > 07:38:56 PM all 1.66 0.00 2.11 0.04 0.00 0.01 > 0.00 3.53 0.00 92.66 > 07:38:56 PM 0 1.99 0.00 5.88 0.04 0.00 0.01 > 0.00 28.11 0.00 63.98 > 07:38:56 PM 1 6.10 0.00 10.23 0.10 0.00 0.05 > 0.00 28.60 0.00 54.93 > 07:38:56 PM 2 0.89 0.00 1.63 0.01 0.00 0.01 > 0.00 0.00 0.00 97.46 > 07:38:56 PM 3 1.60 0.00 1.40 0.01 0.00 0.01 > 0.00 0.00 0.00 96.98 > 07:38:56 PM 4 0.94 0.01 1.13 0.07 0.00 0.02 > 0.00 0.00 0.00 97.82 > 07:38:56 PM 5 1.17 0.00 0.88 0.05 0.00 0.01 > 0.00 0.00 0.00 97.89 > 07:38:56 PM 6 0.82 0.00 1.04 0.01 0.00 0.01 > 0.00 0.00 0.00 98.12 > 07:38:56 PM 7 0.90 0.00 0.80 0.02 0.00 0.01 > 0.00 0.00 0.00 98.27 > 07:38:56 PM 8 2.50 0.00 1.28 0.03 0.00 0.01 > 0.00 0.00 0.00 96.18 > 07:38:56 PM 9 1.21 0.00 2.25 0.01 0.00 0.01 > 0.00 0.00 0.00 96.52 > 07:38:56 PM 10 0.90 0.00 0.90 0.01 0.00 0.01 > 0.00 0.00 0.00 98.19 > 07:38:56 PM 11 2.06 0.00 1.66 0.18 0.00 0.01 > 0.00 0.00 0.00 96.09 > 07:38:56 PM 12 1.06 0.00 0.98 0.01 0.00 0.01 > 0.00 0.00 0.00 97.94 > 07:38:56 PM 13 0.98 0.00 1.48 0.02 0.00 0.01 > 0.00 0.00 0.00 97.51 > 07:38:56 PM 14 1.81 0.00 1.01 0.02 0.00 0.01 > 0.00 0.00 0.00 97.14 > 07:38:56 PM 15 1.57 0.00 1.25 0.02 0.00 0.02 > 0.00 0.00 0.00 97.14 > > Column %guest shows the percentage of time spent by the CPUs to run a > virtual processor. > > Though the inner VM is stopped the VCPUs don't idle completely. > > Idling is implemented via the `wfi` opcode. Could it be that the cores > assigned to VCPUs still receive abundant interrupts? > > Yeah quite possible. Initially I thought it was a qemu tcg bug so I went down the rabit hole and got distracted with the icount thing. I am looking at KVM vcpu timer code first to see if it is constantly firing timer interrupts for some reason. > -- > You received this bug notification because you are subscribed to the bug > report. > https://bugs.launchpad.net/bugs/2112578 > > Title: > riscv64: KVM does not release harts > > Status in linux package in Ubuntu: > New > Status in qemu package in Ubuntu: > Invalid > > Bug description: > In the 6.14.0-13-generic kernel there seems to be a problem with KVM. > > On my amd64 machine I am running a riscv64 machine using QEMU 10 with > 16 cores. Inside the VM I spin up a further machine with 2 cores. Once > KVM emulation is started the load of my amd64 machine rises to > 14/16 > cores for qemu-system-riscv64. KVM seems not to release cores that > were ever used. Top in 1st VM shows 0.25 cores used for 2nd VM. > > The usage on my amd64 machine only drops when unloading the kvm module > in the first VM. > --- > ProblemType: Bug > ApportVersion: 2.32.0-0ubuntu5 > Architecture: riscv64 > AudioDevicesInUse: > USER PID ACCESS COMMAND > /dev/snd/controlC0: zfsdt 2105 F.... wireplumber > /dev/snd/seq: zfsdt 2103 F.... pipewire > CasperMD5json: > { > "result": "skip" > } > CurrentDesktop: XFCE > DistroRelease: Ubuntu 25.10 > InstallationDate: Installed on 2025-03-17 (80 days ago) > InstallationMedia: Ubuntu-Server 25.04 "Plucky Puffin" - Daily riscv64 > (20250316) > Lsusb: > Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub > Bus 001 Device 002: ID 0627:0001 Adomax Technology Co., Ltd QEMU Tablet > Bus 001 Device 003: ID 0627:0001 Adomax Technology Co., Ltd QEMU Tablet > Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub > MachineType: QEMU QEMU Virtual Machine > Package: linux (not installed) > ProcEnviron: > LANG=en_US.UTF-8 > PATH=(custom, no user) > SHELL=/bin/bash > TERM=xterm-256color > ProcFB: 0 virtio_gpudrmfb > ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-6.14.0-13-generic > root=UUID=af336ba2-ea81-4dd5-bada-b3e8e7fb1c58 ro > crashkernel=2G-4G:320M,4G-32G:512M,32G-64G:1024M,64G-128G:2048M,128G-:4096M > ProcVersionSignature: Ubuntu 6.14.0-13.13.2-generic 6.14.0 > PulseList: Error: command ['pacmd', 'list'] failed with exit code 1: No > PulseAudio daemon running, or not running as session daemon. > RelatedPackageVersions: > linux-restricted-modules-6.14.0-13-generic N/A > linux-backports-modules-6.14.0-13-generic N/A > linux-firmware 20250317.git1d4c88ee-0ubuntu1 > RfKill: > > Tags: questing > Uname: Linux 6.14.0-13-generic riscv64 > UpgradeStatus: Upgraded to questing on 2025-05-17 (19 days ago) > UserGroups: N/A > _MarkForUpload: True > acpidump: > > dmi.bios.date: 05/13/2025 > dmi.bios.release: 0.0 > dmi.bios.vendor: Ubuntu distribution of EDK II > dmi.bios.version: 2025.02-8 > dmi.chassis.type: 1 > dmi.chassis.vendor: QEMU > dmi.chassis.version: virt > dmi.modalias: > dmi:bvnUbuntudistributionofEDKII:bvr2025.02-8:bd05/13/2025:br0.0:svnQEMU:pnQEMUVirtualMachine:pvrvirt:cvnQEMU:ct1:cvrvirt:sku: > dmi.product.name: QEMU Virtual Machine > dmi.product.version: virt > dmi.sys.vendor: QEMU > > To manage notifications about this bug go to: > https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2112578/+subscriptions > > -- Regards, Atish -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/2112578 Title: riscv64: KVM does not release harts Status in linux package in Ubuntu: New Status in qemu package in Ubuntu: Invalid Bug description: In the 6.14.0-13-generic kernel there seems to be a problem with KVM. On my amd64 machine I am running a riscv64 machine using QEMU 10 with 16 cores. Inside the VM I spin up a further machine with 2 cores. Once KVM emulation is started the load of my amd64 machine rises to > 14/16 cores for qemu-system-riscv64. KVM seems not to release cores that were ever used. Top in 1st VM shows 0.25 cores used for 2nd VM. The usage on my amd64 machine only drops when unloading the kvm module in the first VM. --- ProblemType: Bug ApportVersion: 2.32.0-0ubuntu5 Architecture: riscv64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC0: zfsdt 2105 F.... wireplumber /dev/snd/seq: zfsdt 2103 F.... pipewire CasperMD5json: { "result": "skip" } CurrentDesktop: XFCE DistroRelease: Ubuntu 25.10 InstallationDate: Installed on 2025-03-17 (80 days ago) InstallationMedia: Ubuntu-Server 25.04 "Plucky Puffin" - Daily riscv64 (20250316) Lsusb: Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 001 Device 002: ID 0627:0001 Adomax Technology Co., Ltd QEMU Tablet Bus 001 Device 003: ID 0627:0001 Adomax Technology Co., Ltd QEMU Tablet Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub MachineType: QEMU QEMU Virtual Machine Package: linux (not installed) ProcEnviron: LANG=en_US.UTF-8 PATH=(custom, no user) SHELL=/bin/bash TERM=xterm-256color ProcFB: 0 virtio_gpudrmfb ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-6.14.0-13-generic root=UUID=af336ba2-ea81-4dd5-bada-b3e8e7fb1c58 ro crashkernel=2G-4G:320M,4G-32G:512M,32G-64G:1024M,64G-128G:2048M,128G-:4096M ProcVersionSignature: Ubuntu 6.14.0-13.13.2-generic 6.14.0 PulseList: Error: command ['pacmd', 'list'] failed with exit code 1: No PulseAudio daemon running, or not running as session daemon. RelatedPackageVersions: linux-restricted-modules-6.14.0-13-generic N/A linux-backports-modules-6.14.0-13-generic N/A linux-firmware 20250317.git1d4c88ee-0ubuntu1 RfKill: Tags: questing Uname: Linux 6.14.0-13-generic riscv64 UpgradeStatus: Upgraded to questing on 2025-05-17 (19 days ago) UserGroups: N/A _MarkForUpload: True acpidump: dmi.bios.date: 05/13/2025 dmi.bios.release: 0.0 dmi.bios.vendor: Ubuntu distribution of EDK II dmi.bios.version: 2025.02-8 dmi.chassis.type: 1 dmi.chassis.vendor: QEMU dmi.chassis.version: virt dmi.modalias: dmi:bvnUbuntudistributionofEDKII:bvr2025.02-8:bd05/13/2025:br0.0:svnQEMU:pnQEMUVirtualMachine:pvrvirt:cvnQEMU:ct1:cvrvirt:sku: dmi.product.name: QEMU Virtual Machine dmi.product.version: virt dmi.sys.vendor: QEMU To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2112578/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
