Re: high host load from vmx_set_supported_cpuid call?

[Gleb Natapov <gleb@redhat.com>]

On Sun, Dec 02, 2012 at 12:41:37PM +0100, Nikola Ciprich wrote:
> Hi,
> 
> while trying to find source of KVM guest slowness, I noticed following in perf top:
> 
>               326.00 19.6% vmx_set_supported_cpuid                        /lib/modules/3.0.53lb6.02/kernel/arch/x86/kvm/kvm-intel.ko    
Something wrong with your symbols. This function cannot take that much.
It is three and a half instruction long and should be called only once
during vm startup.


>               108.00  6.5% kvm_arch_dev_ioctl                             /lib/modules/3.0.53lb6.02/kernel/arch/x86/kvm/kvm.ko          
>               100.00  6.0% tick_dev_program_event                         [kernel.kallsyms]                                             
>                78.00  4.7% __remove_hrtimer                               [kernel.kallsyms]                                             
>                52.00  3.1% acpi_processor_reevaluate_tstate               /lib/modules/3.0.53lb6.02/kernel/drivers/acpi/processor.ko    
>                45.00  2.7% find_busiest_group                             [kernel.kallsyms]                                             
>                43.00  2.6% do_raw_spin_lock                               [kernel.kallsyms]                                             
> 
> my question is, is this normal? I tried googling for vmx_set_supported_cpuid but am not
> really clever about it...
> 
> here's snippet from trace-cmd:
> 
> version = 6
> CPU 11 is empty
> cpus=12
>         qemu-kvm-7766  [000] 235066.551604: kvm_msi_set_irq:      dst 1 vec 51 (LowPrio|logical|edge|rh)
>         qemu-kvm-7766  [000] 235066.551606: kvm_apic_accept_irq:  apicid 0 vec 81 (LowPrio|edge)
>         qemu-kvm-7767  [001] 235066.551618: kvm_inj_virq:         irq 81
>         qemu-kvm-7767  [001] 235066.551620: kvm_entry:            vcpu 0
>         qemu-kvm-7767  [001] 235066.551625: kvm_exit:             reason EPT_MISCONFIG rip 0xffffffff81023d96 info 0 0
>         qemu-kvm-7767  [001] 235066.551630: kvm_emulate_insn:     [FAILED TO PARSE] rip=18446744071578992022 csbase=0 len=2 insn=ARRAY[8b, 00, c9, 89, c0, c3,
>  0f, 1f, 40, 00, 55, 48, 89, e5, 0f] flags=9 failed=0
>         qemu-kvm-7767  [001] 235066.551631: vcpu_match_mmio:      gva 0xffffc900000040f0 gpa 0xfed000f0 Read GPA
>         qemu-kvm-7767  [001] 235066.551632: kvm_mmio:             mmio unsatisfied-read len 4 gpa 0xfed000f0 val 0x0
>         qemu-kvm-7767  [001] 235066.551634: kvm_userspace_exit:   reason KVM_EXIT_MMIO (6)
>         qemu-kvm-7767  [001] 235066.551648: kvm_mmio:             mmio read len 4 gpa 0xfed000f0 val 0xfed25f11
>         qemu-kvm-7767  [001] 235066.551649: kvm_entry:            vcpu 0
>         qemu-kvm-7767  [001] 235066.551650: kvm_exit:             reason EPT_MISCONFIG rip 0xffffffff81023d96 info 0 0
>         qemu-kvm-7767  [001] 235066.551652: kvm_emulate_insn:     [FAILED TO PARSE] rip=18446744071578992022 csbase=0 len=2 insn=ARRAY[8b, 00, c9, 89, c0, c3,
>  0f, 1f, 40, 00, 55, 48, 89, e5, 0f] flags=9 failed=0
>         qemu-kvm-7767  [001] 235066.551652: vcpu_match_mmio:      gva 0xffffc900000040f0 gpa 0xfed000f0 Read GPA
>         qemu-kvm-7767  [001] 235066.551653: kvm_mmio:             mmio unsatisfied-read len 4 gpa 0xfed000f0 val 0x0
>         qemu-kvm-7767  [001] 235066.551653: kvm_userspace_exit:   reason KVM_EXIT_MMIO (6)
>         qemu-kvm-7767  [001] 235066.551656: kvm_mmio:             mmio read len 4 gpa 0xfed000f0 val 0xfed26450
>         qemu-kvm-7767  [001] 235066.551657: kvm_entry:            vcpu 0
>         qemu-kvm-7767  [001] 235066.551659: kvm_exit:             reason EPT_MISCONFIG rip 0xffffffff81023d96 info 0 0
>         qemu-kvm-7767  [001] 235066.551660: kvm_emulate_insn:     [FAILED TO PARSE] rip=18446744071578992022 csbase=0 len=2 insn=ARRAY[8b, 00, c9, 89, c0, c3,
>  0f, 1f, 40, 00, 55, 48, 89, e5, 0f] flags=9 failed=0
>         qemu-kvm-7767  [001] 235066.551660: vcpu_match_mmio:      gva 0xffffc900000040f0 gpa 0xfed000f0 Read GPA
>         qemu-kvm-7767  [001] 235066.551660: kvm_mmio:             mmio unsatisfied-read len 4 gpa 0xfed000f0 val 0x0
>         qemu-kvm-7767  [001] 235066.551661: kvm_userspace_exit:   reason KVM_EXIT_MMIO (6)
>         qemu-kvm-7767  [001] 235066.551663: kvm_mmio:             mmio read len 4 gpa 0xfed000f0 val 0xfed2672b
>         qemu-kvm-7767  [001] 235066.551664: kvm_entry:            vcpu 0
>         qemu-kvm-7767  [001] 235066.551667: kvm_exit:             reason APIC_ACCESS rip 0xffffffff810219eb info 10b0 0
>         qemu-kvm-7767  [001] 235066.551667: kvm_apic:             apic_write APIC_EOI = 0x0
>         qemu-kvm-7767  [001] 235066.551668: kvm_eoi:              apicid 0 vector 81
>         qemu-kvm-7767  [001] 235066.551668: kvm_entry:            vcpu 0
>         qemu-kvm-7767  [001] 235066.551681: kvm_exit:             reason EPT_MISCONFIG rip 0xffffffff81023d96 info 0 0
>         qemu-kvm-7767  [001] 235066.551682: kvm_emulate_insn:     [FAILED TO PARSE] rip=18446744071578992022 csbase=0 len=2 insn=ARRAY[8b, 00, c9, 89, c0, c3,
>  0f, 1f, 40, 00, 55, 48, 89, e5, 0f] flags=9 failed=0
>         qemu-kvm-7767  [001] 235066.551683: vcpu_match_mmio:      gva 0xffffc900000040f0 gpa 0xfed000f0 Read GPA
>         qemu-kvm-7767  [001] 235066.551683: kvm_mmio:             mmio unsatisfied-read len 4 gpa 0xfed000f0 val 0x0
>         qemu-kvm-7767  [001] 235066.551684: kvm_userspace_exit:   reason KVM_EXIT_MMIO (6)
> 
> (I can store trace-cmd file somewhere if it can help).
> 
> This host is x86_64 centos6, running kernel 3.0.53 with kvm-kmod-3.6 and qemu-kvm-1.2.0
> 
> If I could provide more information, I'll be happy to do so..
> 
> BR
> 
> nik
> 
> 
> 
> 
> -- 
> -------------------------------------
> Ing. Nikola CIPRICH
> LinuxBox.cz, s.r.o.
> 28. rijna 168, 709 00 Ostrava
> 
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> 
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--
			Gleb.