Hi Paolo, Thanks for your quick answer. Are you using only 2 CPUs at 100%, or are you using 9 CPUs at a total of 200%? Inside the VM, a top command show that we are using 2 CPU @ 100%: https://framadrop.org/r/gNf3erJVf6#t2HLIpzPHGtxHzHeLrnGGjsRSZZpmv9HPVZt/LIIP8s= >From the hypervisor (ie, *outside* the vm), a top command show that the VM consuming 9 cpu: https://framadrop.org/r/-FmrBhMGX5#q/6aZ8Fq2Mnuzz3+6F/pa83U+jzPox1hd984tw7DkuA= So, if I'm understanding you correctly, an parameter of kernel of our VM is idel=poll that we should change? Thanks again, -----Message d'origine----- De : Paolo Bonzini <pbonzini@xxxxxxxxxx> Envoyé : mardi 7 janvier 2020 17:59 À : Gregory Esnaud <Gregory.ESNAUD@xxxxxxxx>; kvm@xxxxxxxxxxxxxxx Objet : Re: [Newbie question] Why usage of CPU inside VM and outside VM is different On 07/01/20 16:57, Gregory Esnaud wrote: > > From an hypervisor (via top command) point of view our VM is consuming > 9 CPU (900%). This was reported by our platform provider. > From a VM point of view we are consuming only 2 CPU (200%), with a top > also. > > Our provider claim us to explain why we are consuming so much CPU. > But we cannot troubleshoot the infra as it's not our responsibility. > From our point of view, everything is ok. Are you using only 2 CPUs at 100%, or are you using 9 CPUs at a total of 200%? If the former, it is possible that you are using something like idle=poll, so the machine _is_ idle but still consuming 100% host CPU. This is something that you should know, however. If the latter, the host is probably doing a little bit of busy waiting to improve your performance. The provider can disable it using the kvm.halt_poll_ns=0 module parameter and there is nothing that you can do about it. But it is unlikely that it causes the utilization to jump so much. Paolo
