I'm getting "Marking TSC unstable due to clocksource watchdog" after some hours of uptime.
System is Threadripper 3960x, Asus TRX40-pro with the latest available bios, 8x8G 3200 sticks.
```
[1198064.004082] clocksource: timekeeping watchdog on CPU46: hpet retried 2 times before success
[1198417.504375] clocksource: timekeeping watchdog on CPU33: hpet retried 2 times before success
[1205730.408893] clocksource: timekeeping watchdog on CPU19: hpet retried 2 times before success
[1208535.367247] clocksource: timekeeping watchdog on CPU13: hpet retried 2 times before success
[1210111.861844] clocksource: timekeeping watchdog on CPU46: hpet retried 2 times before success
[1211693.859893] clocksource: timekeeping watchdog on CPU42: hpet retried 2 times before success
[1212112.349543] clocksource: timekeeping watchdog on CPU15: hpet retried 2 times before success
[1212222.331692] clocksource: timekeeping watchdog on CPU43: hpet retried 2 times before success
[1216504.296297] clocksource: timekeeping watchdog on CPU15: hpet retried 2 times before success
[1219421.252785] clocksource: timekeeping watchdog on CPU41: hpet retried 2 times before success
[1220879.219092] clocksource: timekeeping watchdog on CPU29: hpet retried 3 times before success
[1223252.214573] clocksource: timekeeping watchdog on CPU23: hpet retried 2 times before success
[1223270.710066] clocksource: timekeeping watchdog on CPU12: hpet retried 2 times before success
[1223329.717788] clocksource: timekeeping watchdog on CPU34: hpet retried 2 times before success
[1223361.205306] clocksource: timekeeping watchdog on CPU1: hpet retried 2 times before success
[1223394.196860] clocksource: timekeeping watchdog on CPU19: hpet retried 2 times before success
[1225092.672343] clocksource: timekeeping watchdog on CPU8: hpet retried 2 times before success
[1226989.672841] clocksource: timekeeping watchdog on CPU10: hpet retried 2 times before success
[1229157.645192] clocksource: timekeeping watchdog on CPU26: hpet retried 2 times before success
[1229317.647249] clocksource: timekeeping watchdog on CPU10: hpet retried 2 times before success
[1230445.628034] clocksource: timekeeping watchdog on CPU10: hpet retried 2 times before success
[1230577.627173] clocksource: timekeeping watchdog on CPU34: hpet retried 2 times before success
[1231853.612183] clocksource: timekeeping watchdog on CPU42: hpet retried 2 times before success
[1236160.536165] clocksource: timekeeping watchdog on CPU16: hpet retried 2 times before success
[1236387.541082] clocksource: timekeeping watchdog on CPU38: hpet retried 2 times before success
[1237260.522970] clocksource: timekeeping watchdog on CPU8: hpet retried 2 times before success
[1238370.525093] clocksource: timekeeping watchdog on CPU20: hpet retried 2 times before success
[1238988.505826] clocksource: timekeeping watchdog on CPU8: hpet retried 2 times before success
[1239261.523627] clocksource: timekeeping watchdog on CPU26: hpet retried 2 times before success
[1239493.008794] clocksource: timekeeping watchdog on CPU9: hpet retried 3 times before success
[1240244.488131] clocksource: timekeeping watchdog on CPU24: hpet retried 2 times before success
[1240439.493726] clocksource: timekeeping watchdog on CPU30: hpet retried 2 times before success
[1241095.485836] clocksource: timekeeping watchdog on CPU46: hpet read-back delay of 118590ns, attempt 4, marking unstable
[1241095.485844] tsc: Marking TSC unstable due to clocksource watchdog
[1241095.485854] TSC found unstable after boot, most likely due to broken BIOS. Use 'tsc=unstable'.
[1241095.485856] sched_clock: Marking unstable (1241111549654842, -16063798926)<-(1241095594330567, -108480761)
[1241095.486154] clocksource: Switched to clocksource hpet
```
After this occurs - the VMs start working very sluggish.
PVE 6.4-15
```
proxmox-ve: 6.4-1 (running kernel: 5.4.195-1-pve) pve-manager: 6.4-15 (running version: 6.4-15/af7986e6) pve-kernel-5.4: 6.4-19 pve-kernel-helper: 6.4-19 pve-kernel-5.3: 6.1-6 pve-kernel-5.0: 6.0-11 pve-kernel-5.4.195-1-pve: 5.4.195-1 pve-kernel-5.4.189-2-pve: 5.4.189-2 pve-kernel-5.4.178-1-pve: 5.4.178-1 pve-kernel-5.4.174-2-pve: 5.4.174-2 pve-kernel-5.4.166-1-pve: 5.4.166-1 pve-kernel-5.4.162-1-pve: 5.4.162-2 pve-kernel-5.4.157-1-pve: 5.4.157-1 pve-kernel-5.4.143-1-pve: 5.4.143-1 pve-kernel-5.4.140-1-pve: 5.4.140-1 pve-kernel-5.4.128-1-pve: 5.4.128-2 pve-kernel-5.4.124-1-pve: 5.4.124-2 pve-kernel-5.4.119-1-pve: 5.4.119-1 pve-kernel-5.4.114-1-pve: 5.4.114-1 pve-kernel-5.4.106-1-pve: 5.4.106-1 pve-kernel-5.4.103-1-pve: 5.4.103-1 pve-kernel-5.4.101-1-pve: 5.4.101-1 pve-kernel-5.4.98-1-pve: 5.4.98-1 pve-kernel-5.4.78-2-pve: 5.4.78-2 pve-kernel-5.4.78-1-pve: 5.4.78-1 pve-kernel-5.3.18-3-pve: 5.3.18-3 pve-kernel-5.0.21-5-pve: 5.0.21-10 pve-kernel-5.0.15-1-pve: 5.0.15-1 ceph-fuse: 12.2.11+dfsg1-2.1+b1 corosync: 3.1.5-pve2~bpo10+1 criu: 3.11-3 glusterfs-client: 5.5-3 ifupdown: not correctly installed ifupdown2: 3.0.0-1+pve4~bpo10 ksm-control-daemon: 1.3-1 libjs-extjs: 6.0.1-10 libknet1: 1.22-pve2~bpo10+1 libproxmox-acme-perl: 1.1.0 libproxmox-backup-qemu0: 1.1.0-1 libpve-access-control: 6.4-3 libpve-apiclient-perl: 3.1-3 libpve-common-perl: 6.4-5 libpve-guest-common-perl: 3.1-5 libpve-http-server-perl: 3.2-5 libpve-storage-perl: 6.4-1 libqb0: 1.0.5-1 libspice-server1: 0.14.2-4~pve6+1 lvm2: 2.03.02-pve4 lxc-pve: 4.0.6-2 lxcfs: 4.0.6-pve1 novnc-pve: 1.1.0-1 openvswitch-switch: 2.12.3-1 proxmox-backup-client: 1.1.14-1 proxmox-mini-journalreader: 1.1-1 proxmox-widget-toolkit: 2.6-2 pve-cluster: 6.4-1 pve-container: 3.3-6 pve-docs: 6.4-2 pve-edk2-firmware: 2.20200531-1 pve-firewall: 4.1-4 pve-firmware: 3.3-2 pve-ha-manager: 3.1-1 pve-i18n: 2.3-1 pve-qemu-kvm: 5.2.0-8 pve-xtermjs: 4.7.0-3 qemu-server: 6.4-2 smartmontools: 7.2-pve2 spiceterm: 3.1-1 vncterm: 1.6-2 zfsutils-linux: 2.0.7-pve1
```
System is Threadripper 3960x, Asus TRX40-pro with the latest available bios, 8x8G 3200 sticks.
```
[1198064.004082] clocksource: timekeeping watchdog on CPU46: hpet retried 2 times before success
[1198417.504375] clocksource: timekeeping watchdog on CPU33: hpet retried 2 times before success
[1205730.408893] clocksource: timekeeping watchdog on CPU19: hpet retried 2 times before success
[1208535.367247] clocksource: timekeeping watchdog on CPU13: hpet retried 2 times before success
[1210111.861844] clocksource: timekeeping watchdog on CPU46: hpet retried 2 times before success
[1211693.859893] clocksource: timekeeping watchdog on CPU42: hpet retried 2 times before success
[1212112.349543] clocksource: timekeeping watchdog on CPU15: hpet retried 2 times before success
[1212222.331692] clocksource: timekeeping watchdog on CPU43: hpet retried 2 times before success
[1216504.296297] clocksource: timekeeping watchdog on CPU15: hpet retried 2 times before success
[1219421.252785] clocksource: timekeeping watchdog on CPU41: hpet retried 2 times before success
[1220879.219092] clocksource: timekeeping watchdog on CPU29: hpet retried 3 times before success
[1223252.214573] clocksource: timekeeping watchdog on CPU23: hpet retried 2 times before success
[1223270.710066] clocksource: timekeeping watchdog on CPU12: hpet retried 2 times before success
[1223329.717788] clocksource: timekeeping watchdog on CPU34: hpet retried 2 times before success
[1223361.205306] clocksource: timekeeping watchdog on CPU1: hpet retried 2 times before success
[1223394.196860] clocksource: timekeeping watchdog on CPU19: hpet retried 2 times before success
[1225092.672343] clocksource: timekeeping watchdog on CPU8: hpet retried 2 times before success
[1226989.672841] clocksource: timekeeping watchdog on CPU10: hpet retried 2 times before success
[1229157.645192] clocksource: timekeeping watchdog on CPU26: hpet retried 2 times before success
[1229317.647249] clocksource: timekeeping watchdog on CPU10: hpet retried 2 times before success
[1230445.628034] clocksource: timekeeping watchdog on CPU10: hpet retried 2 times before success
[1230577.627173] clocksource: timekeeping watchdog on CPU34: hpet retried 2 times before success
[1231853.612183] clocksource: timekeeping watchdog on CPU42: hpet retried 2 times before success
[1236160.536165] clocksource: timekeeping watchdog on CPU16: hpet retried 2 times before success
[1236387.541082] clocksource: timekeeping watchdog on CPU38: hpet retried 2 times before success
[1237260.522970] clocksource: timekeeping watchdog on CPU8: hpet retried 2 times before success
[1238370.525093] clocksource: timekeeping watchdog on CPU20: hpet retried 2 times before success
[1238988.505826] clocksource: timekeeping watchdog on CPU8: hpet retried 2 times before success
[1239261.523627] clocksource: timekeeping watchdog on CPU26: hpet retried 2 times before success
[1239493.008794] clocksource: timekeeping watchdog on CPU9: hpet retried 3 times before success
[1240244.488131] clocksource: timekeeping watchdog on CPU24: hpet retried 2 times before success
[1240439.493726] clocksource: timekeeping watchdog on CPU30: hpet retried 2 times before success
[1241095.485836] clocksource: timekeeping watchdog on CPU46: hpet read-back delay of 118590ns, attempt 4, marking unstable
[1241095.485844] tsc: Marking TSC unstable due to clocksource watchdog
[1241095.485854] TSC found unstable after boot, most likely due to broken BIOS. Use 'tsc=unstable'.
[1241095.485856] sched_clock: Marking unstable (1241111549654842, -16063798926)<-(1241095594330567, -108480761)
[1241095.486154] clocksource: Switched to clocksource hpet
```
After this occurs - the VMs start working very sluggish.
PVE 6.4-15
```
proxmox-ve: 6.4-1 (running kernel: 5.4.195-1-pve) pve-manager: 6.4-15 (running version: 6.4-15/af7986e6) pve-kernel-5.4: 6.4-19 pve-kernel-helper: 6.4-19 pve-kernel-5.3: 6.1-6 pve-kernel-5.0: 6.0-11 pve-kernel-5.4.195-1-pve: 5.4.195-1 pve-kernel-5.4.189-2-pve: 5.4.189-2 pve-kernel-5.4.178-1-pve: 5.4.178-1 pve-kernel-5.4.174-2-pve: 5.4.174-2 pve-kernel-5.4.166-1-pve: 5.4.166-1 pve-kernel-5.4.162-1-pve: 5.4.162-2 pve-kernel-5.4.157-1-pve: 5.4.157-1 pve-kernel-5.4.143-1-pve: 5.4.143-1 pve-kernel-5.4.140-1-pve: 5.4.140-1 pve-kernel-5.4.128-1-pve: 5.4.128-2 pve-kernel-5.4.124-1-pve: 5.4.124-2 pve-kernel-5.4.119-1-pve: 5.4.119-1 pve-kernel-5.4.114-1-pve: 5.4.114-1 pve-kernel-5.4.106-1-pve: 5.4.106-1 pve-kernel-5.4.103-1-pve: 5.4.103-1 pve-kernel-5.4.101-1-pve: 5.4.101-1 pve-kernel-5.4.98-1-pve: 5.4.98-1 pve-kernel-5.4.78-2-pve: 5.4.78-2 pve-kernel-5.4.78-1-pve: 5.4.78-1 pve-kernel-5.3.18-3-pve: 5.3.18-3 pve-kernel-5.0.21-5-pve: 5.0.21-10 pve-kernel-5.0.15-1-pve: 5.0.15-1 ceph-fuse: 12.2.11+dfsg1-2.1+b1 corosync: 3.1.5-pve2~bpo10+1 criu: 3.11-3 glusterfs-client: 5.5-3 ifupdown: not correctly installed ifupdown2: 3.0.0-1+pve4~bpo10 ksm-control-daemon: 1.3-1 libjs-extjs: 6.0.1-10 libknet1: 1.22-pve2~bpo10+1 libproxmox-acme-perl: 1.1.0 libproxmox-backup-qemu0: 1.1.0-1 libpve-access-control: 6.4-3 libpve-apiclient-perl: 3.1-3 libpve-common-perl: 6.4-5 libpve-guest-common-perl: 3.1-5 libpve-http-server-perl: 3.2-5 libpve-storage-perl: 6.4-1 libqb0: 1.0.5-1 libspice-server1: 0.14.2-4~pve6+1 lvm2: 2.03.02-pve4 lxc-pve: 4.0.6-2 lxcfs: 4.0.6-pve1 novnc-pve: 1.1.0-1 openvswitch-switch: 2.12.3-1 proxmox-backup-client: 1.1.14-1 proxmox-mini-journalreader: 1.1-1 proxmox-widget-toolkit: 2.6-2 pve-cluster: 6.4-1 pve-container: 3.3-6 pve-docs: 6.4-2 pve-edk2-firmware: 2.20200531-1 pve-firewall: 4.1-4 pve-firmware: 3.3-2 pve-ha-manager: 3.1-1 pve-i18n: 2.3-1 pve-qemu-kvm: 5.2.0-8 pve-xtermjs: 4.7.0-3 qemu-server: 6.4-2 smartmontools: 7.2-pve2 spiceterm: 3.1-1 vncterm: 1.6-2 zfsutils-linux: 2.0.7-pve1
```