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
