abnormal cpu usage

menelaostrik

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Sep 7, 2020
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I have a host running only one vm with a e5-2667v4 cpu(8core-16threads)
i have assigned all threads to a vm which is only vm on the host.
i can see a ~900% cpu usage on the kvm process (all other processes of the host doesn't consume more than 50%) while at the same time the vm iis at ~40-45% total cpu load.

i can't see this kind of difference in any other host/vm
usually they're on par with minus differences.

Do you know what could be causing this?
thank you for your time
 
900% CPU usage with 16 threads would mean KVM is using 56% of your CPU performance. This isn't much more than the 40-45% you see in the VM.

Maybe you should show us your VMs config file.
 
900% CPU usage with 16 threads would mean KVM is using 56% of your CPU performance. This isn't much more than the 40-45% you see in the VM.

Maybe you should show us your VMs config file.
sure, here is the vm config:
root@hyper2:/etc/pve/qemu-server# cat 500.conf agent: 1 boot: order=scsi0;ide2;net0 cores: 16 cpu: host ide2: none,media=cdrom memory: 55000 name: Cpanel net0: virtio=D2:BE:0B:96:8A:22,bridge=vmbr0,firewall=1 numa: 0 onboot: 1 ostype: l26 scsi0: local-zfs:vm-500-disk-0,iops_rd=2500,iops_rd_max=4000,iops_wr=2500,iops_wr_max=4000,mbps_rd=200,mbps_rd_max=400,mbps_wr=200,mbps_wr_max=400,size=100G,ssd=1 scsi1: local-zfs:vm-500-disk-1,iops_rd=2500,iops_rd_max=4000,iops_wr=2500,iops_wr_max=4000,mbps_rd=200,mbps_rd_max=400,mbps_wr=200,mbps_wr_max=400,size=400G,ssd=1 scsihw: virtio-scsi-pci smbios1: uuid=f26d0b0a-16f8-4f27-9ed3-6b33158c6995 sockets: 1 vga: virtio vmgenid: 074a61e4-328a-4061-b5eb-20861ea2265e root@hyper2:/etc/pve/qemu-server#

the load averages on the host are approximately double to load averages of the VM constantly.

on another host the vm/host load averages are about the same, so this intrigued my curiocity as to why this is happening.
After further investigation i can see differences in /proc/cpuinfo
i'm pasting the last entry of those as well

on host:
processor : 15 vendor_id : GenuineIntel cpu family : 6 model : 79 model name : Intel(R) Xeon(R) CPU E5-2667 v4 @ 3.20GHz stepping : 1 microcode : 0xb000040 cpu MHz : 3196.251 cache size : 25600 KB physical id : 0 siblings : 16 core id : 12 cpu cores : 8 apicid : 25 initial apicid : 25 fpu : yes fpu_exception : yes cpuid level : 20 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 sdbg fma cx16 xtpr pdcm pcid dca sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm 3dnowprefetch cpuid_fault epb cat_l3 cdp_l3 invpcid_single pti intel_ppin ssbd ibrs ibpb stibp tpr_shadow vnmi flexpriority ept vpid ept_ad fsgsbase tsc_adjust bmi1 hle avx2 smep bmi2 erms invpcid rtm cqm rdt_a rdseed adx smap intel_pt xsaveopt cqm_llc cqm_occup_llc cqm_mbm_total cqm_mbm_local dtherm ida arat pln pts md_clear flush_l1d bugs : cpu_meltdown spectre_v1 spectre_v2 spec_store_bypass l1tf mds swapgs taa itlb_multihit bogomips : 6392.50 clflush size : 64 cache_alignment : 64 address sizes : 46 bits physical, 48 bits virtual power management:
and on the VM:
processor : 15 vendor_id : GenuineIntel cpu family : 6 model : 79 model name : Intel(R) Xeon(R) CPU E5-2667 v4 @ 3.20GHz stepping : 1 microcode : 0x1 cpu MHz : 3196.296 cache size : 16384 KB physical id : 0 siblings : 16 core id : 15 cpu cores : 16 apicid : 15 initial apicid : 15 fpu : yes fpu_exception : yes cpuid level : 20 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ss ht syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon rep_good nopl xtopology cpuid tsc_known_freq pni pclmulqdq ssse3 fma cx16 pcid sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand hypervisor lahf_lm abm 3dnowprefetch cpuid_fault invpcid_single pti ssbd ibrs ibpb stibp fsgsbase tsc_adjust bmi1 hle avx2 smep bmi2 erms invpcid rtm rdseed adx smap xsaveopt arat umip md_clear arch_capabilities bugs : cpu_meltdown spectre_v1 spectre_v2 spec_store_bypass l1tf mds swapgs taa bogomips : 6392.59 clflush size : 64 cache_alignment : 64 address sizes : 40 bits physical, 48 bits virtual power management:
 

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