Hello, I can t enable PCID/Spectre-ctrl, host does not support it Same results using CPU type host I notice that GUEST %CPU decrease by allocating a single vcpu In that situation I have same 7% CPU on PROXMOX and VMWARE GUESTS But on host side it s drastically different On VMWARE HOST : 8% CPU On PROXMOX HOST : 50% CPU (40% qemu process and 10% vhost kernel thread)
I also notice that with single vcpu ksoftirq CPU time consuming on GUEST is close to zero With dual vcpu (or more) ksoftirq increase even when GUEST is idling It appears to be an improper use of the CPU whether with the HOST CPU type or kvm64 I started with last stable proxmox ISO (5.2), I dont know how to improve CPU utilisation Do you notice the same behavior, GUEST/HOST CPU usage difference ? Thank you -----Message d'origine----- De : pve-user [mailto:[email protected]] De la part de Alwin Antreich Envoyé : samedi 9 juin 2018 19:48 À : PVE User List <[email protected]> Objet : ###SPAM### Re: [PVE-User] high cpu load on 100mbits/sec download with virtio nic On Fri, Jun 08, 2018 at 07:39:17AM +0000, Maxime AUGER wrote: > Hello, > > Let me clarify my statement. > GUEST CPU load is acceptable (25% of a single CPU) It is the > cumulative load of the kvm process and the vhost thread that is high, > on the HOST side kvm-thread-1=30% kvm-thred-2=30% vhost(net)=10% 70% > CPU without i/o disk (-O /dev/null) > > it is x10 the load observed with the same conditions under old Vmware > ESXi (same GUEST system and wget process) I think it is a kvm issue, > but I'm curious about proxmox's positioning in relation to this > performance level > > > -----Message d'origine----- > De : pve-user [mailto:[email protected]] De la part de > Josh Knight Envoyé : jeudi 7 juin 2018 20:47 À : PVE User List > <[email protected]> Objet : Re: [PVE-User] high cpu load on > 100mbits/sec download with virtio nic > > I'm not convinced this is a proxmox issue, or even an issue to begin with. > > I'm running proxmox 5.1-49, in my Linux 4.1 guest when I run wget -O > /dev/null <https to ~1.2GB iso> I'm seeing ~30% according to top as well. > > PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND > 12788 root 20 0 65512 7616 5988 S 31.3 0.1 0:03.00 wget > > > Even on a physical box running Ubuntu I'm getting around 20-30% or more. > > PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND > 36070 root 20 0 32888 4028 3576 S 37.6 0.0 0:03.15 wget > > > This could be an issue/quirk with the way top is calculating cpu usage, or > it's just a process using available cpu as normal. I couldn't reproduce high > load using ping -f from a remote host to my VM, and iotop confirmed that -O > /dev/null wasn't somehow writing to disk. I was able to lower the CPU usage > by running wget with --limit-rate=. > > Related, I would not recommend macvtap if you're running routers. At > least running on an Ubuntu 16.04 host, under load of ~1Gb we were > seeing anywhere from 0.01% to 0.16% packet loss before it reached the > guest's virtio interface. We switched to linux bridge and then > finally to openvswitch with the default switching config (no custom > openflow rules.) > > > Josh Knight > I guess, this could be well related to the Meltdown/Spectre mitigation. At least it would fit to the "old" ESXi showing a different performance hit. Try to set the CPU type to host or activate PCID/Spectre-ctrl if applicable. https://pve.proxmox.com/pve-docs/chapter-qm.html#qm_cpu -- Cheers, Alwin _______________________________________________ pve-user mailing list [email protected] https://pve.proxmox.com/cgi-bin/mailman/listinfo/pve-user _______________________________________________ pve-user mailing list [email protected] https://pve.proxmox.com/cgi-bin/mailman/listinfo/pve-user
