For myself KSM is unpredictable feature. The problem is Compute, just this node does "copy on write" , so only Compute. My concern exactly is where would it lead to worse or better Guest behavior ? I am not expecting complete fix. I would track via top/htop and dmesg via Cron on 1-2 hr period. ________________________________ From: centos-virt-bounces at centos.org <centos-virt-bounces at centos.org> on behalf of Laurentiu Soica <laurentiu at soica.ro> Sent: Wednesday, August 17, 2016 6:38 AM To: Discussion about the virtualization on CentOS Subject: Re: [CentOS-virt] Nested KVM issue Both baremetal and compute ? Are there any other metrics do you consider useful to collect for troubleshooting purposes ? În mie., 17 aug. 2016 la 13:04, Boris Derzhavets <bderzhavets at hotmail.com<mailto:bderzhavets at hotmail.com>> a scris: It sounds weird, but attempt to disable KSM and see would it help or no ? ________________________________ From: centos-virt-bounces at centos.org<mailto:centos-virt-bounces at centos.org> <centos-virt-bounces at centos.org<mailto:centos-virt-bounces at centos.org>> on behalf of Laurentiu Soica <laurentiu at soica.ro<mailto:laurentiu at soica.ro>> Sent: Wednesday, August 17, 2016 4:56 AM To: Discussion about the virtualization on CentOS Subject: Re: [CentOS-virt] Nested KVM issue Enabled the logging on both compute and baremetal. Nothing strange in logs: on baremetal : Wed Aug 17 11:51:01 EEST 2016: committed 62310764 free 58501808 Wed Aug 17 11:51:01 EEST 2016: 87025667 < 123574516 and free > 24714903, stop ksm on compute: Wed Aug 17 08:52:52 UTC 2016: committed 24547132 free 76730936 Wed Aug 17 08:52:52 UTC 2016: 45139624 < 102962460 and free > 20592492, stop ksm and the compute node is again at 100% CPU utilization. În mar., 16 aug. 2016 la 15:26, Boris Derzhavets <bderzhavets at hotmail.com<mailto:bderzhavets at hotmail.com>> a scris: I would enable ksmtuned logging ,if it has been done verify logs ________________________________ From: centos-virt-bounces at centos.org<mailto:centos-virt-bounces at centos.org> <centos-virt-bounces at centos.org<mailto:centos-virt-bounces at centos.org>> on behalf of Laurentiu Soica <laurentiu at soica.ro<mailto:laurentiu at soica.ro>> Sent: Tuesday, August 16, 2016 7:16 AM To: Discussion about the virtualization on CentOS Subject: Re: [CentOS-virt] Nested KVM issue Yes. It is on both baremetal and compute node. În mar., 16 aug. 2016 la 13:37, Boris Derzhavets <bderzhavets at hotmail.com<mailto:bderzhavets at hotmail.com>> a scris: Is KSM enabled on your Compute Nodes ( presuming CentOS 7.2 on bare metal ) ? ________________________________ From: centos-virt-bounces at centos.org<mailto:centos-virt-bounces at centos.org> <centos-virt-bounces at centos.org<mailto:centos-virt-bounces at centos.org>> on behalf of Laurentiu Soica <laurentiu at soica.ro<mailto:laurentiu at soica.ro>> Sent: Tuesday, August 16, 2016 5:25 AM To: Discussion about the virtualization on CentOS Subject: Re: [CentOS-virt] Nested KVM issue Running the compute node for several days simply triggers it. În mar., 16 aug. 2016 la 12:12, Boris Derzhavets <bderzhavets at hotmail.com<mailto:bderzhavets at hotmail.com>> a scris: Sorry, How you trigger the problem ? B. ________________________________ From: centos-virt-bounces at centos.org<mailto:centos-virt-bounces at centos.org> <centos-virt-bounces at centos.org<mailto:centos-virt-bounces at centos.org>> on behalf of Laurentiu Soica <laurentiu at soica.ro<mailto:laurentiu at soica.ro>> Sent: Tuesday, August 16, 2016 3:28 AM To: Discussion about the virtualization on CentOS Subject: Re: [CentOS-virt] Nested KVM issue Hello, The issue reproduced again and it doesn't look like a swap problem. Some details: on the baremetal, from top: top - 08:08:52 up 5 days, 16:43, 3 users, load average: 36.19, 36.05, 36.05 Tasks: 493 total, 1 running, 492 sleeping, 0 stopped, 0 zombie %Cpu(s): 3.5 us, 87.9 sy, 0.0 ni, 8.6 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st KiB Mem : 12357451+total, 14296000 free, 65634428 used, 43644088 buff/cache KiB Swap: 4194300 total, 4073868 free, 120432 used. 56953888 avail Mem 19158 qemu 20 0 0.098t 0.041t 10476 S 3650 35.6 13048:24 qemu-kvm The compute node has 36 CPUs and the usage is now 100%. There are more than 50 GB of memory still available on the baremetal. The swap is barely used, 120 MB. On compute node, from top: top - 05:11:58 up 1 day, 15:08, 2 users, load average: 40.46, 40.49, 40.74 %Cpu(s): 99.1 us, 0.7 sy, 0.0 ni, 0.0 id, 0.0 wa, 0.0 hi, 0.1 si, 0.1 st KiB Mem : 10296246+total, 78079936 free, 23671360 used, 1211160 buff/cache KiB Swap: 0 total, 0 free, 0 used. 78939968 avail Mem PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 6032 qemu 20 0 10.601g 1.272g 12964 S 400.0 1.3 588:40.39 qemu-kvm 5673 qemu 20 0 10.602g 1.006g 13020 S 399.7 1.0 1161:47 qemu-kvm 5998 qemu 20 0 10.601g 1.192g 13028 S 367.9 1.2 1544:30 qemu-kvm 5951 qemu 20 0 10.601g 1.246g 13020 S 348.3 1.3 1547:38 qemu-kvm 5750 qemu 20 0 10.599g 990136 13060 S 339.1 1.0 1152:25 qemu-kvm 5752 qemu 20 0 10.598g 1.426g 13040 S 313.9 1.5 663:13.65 qemu-kvm .... There are more than 70 GB of memory available on the compute node. All VMs are using 100% their CPUs and they are not accessible anymore. Laurentiu În dum., 14 aug. 2016 la 21:44, Boris Derzhavets <bderzhavets at hotmail.com<mailto:bderzhavets at hotmail.com>> a scris: ________________________________ From: centos-virt-bounces at centos.org<mailto:centos-virt-bounces at centos.org> <centos-virt-bounces at centos.org<mailto:centos-virt-bounces at centos.org>> on behalf of Laurentiu Soica <laurentiu at soica.ro<mailto:laurentiu at soica.ro>> Sent: Sunday, August 14, 2016 10:17 AM To: Discussion about the virtualization on CentOS Subject: Re: [CentOS-virt] Nested KVM issue More details on the subject: I suppose it is a nested KVM issue because it raised after I enabled the nested KVM feature. Without it, anyway, the second level VMs are unusable in terms of performance. I am using CentOS 7 with: kernel: 3.10.0-327.22.2.el7.x86_64 qemu-kvm:1.5.3-105.el7_2.4 libvirt:1.2.17-13.el7_2.5 on both the baremetal and the compute VM. Please, post 1) # virsh dumpxml VM-L1 ( where on L1 level you expect nested KVM to appear) 2) Login into VM-L1 and run :- # lsmod | grep kvm 3) I need outputs from VM-L1 ( in case it is Compute Node ) # cat /etc/nova/nova.conf | grep virt_type # cat /etc/nova/nova.conf | grep cpu_mode Boris. The only workaround now is to shutdown the compute VM and start it back from baremetal with virsh start. A simple restart of the compute node doesn't help. It looks like the qemu-kvm process corresponding to the compute VM is the problem. Laurentiu În dum., 14 aug. 2016 la 00:19, Laurentiu Soica <laurentiu at soica.ro<mailto:laurentiu at soica.ro>> a scris: Hello, I have an OpenStack setup in virtual environment on CentOS 7. The baremetal has nested KVM enabled and 1 compute node as a VM. Inside the compute node I have multiple VMs running. After about every 3 days the VMs get inaccessible and the compute node reports high CPU usage. The qemu-kvm process for each VM inside the compute node reports full CPU usage. Please help me with some hints to debug this issue. 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