Hello, it's not my intention, my goal is to migrate on KVM a hundred VM currently driven by VMWARE I am aware of the architecture differences between vmware and kvm the comparison may make no sense but I can't migrate without doing a minimum of validation testing Currently I notice an overhead which is likely to be problematic to scale if this is the normal behavior of KVM virtualization I would load less VM but that doesn't seem to be the way it is. So to discern this I would like to have your feedback the key question I ask On your PROXMOX setup is the visible CPU usage on the linux GUEST and HOST sides are drastically different on idle ? and with a wget -O /dev/null ... at 100mbits rate ?
-----Message d'origine----- De : Woods, Ken A (DNR) [mailto:[email protected]] Envoyé : mardi 12 juin 2018 18:20 À : Maxime AUGER <[email protected]> Objet : Re: [PVE-User] high cpu load on 100mbits/sec download with virtio nic Are you sure your goal is to not to just trash proxmox? > On Jun 12, 2018, at 08:05, Maxime AUGER <[email protected]> wrote: > > 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 _______________________________________________ pve-user mailing list [email protected] https://pve.proxmox.com/cgi-bin/mailman/listinfo/pve-user
