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A.4. kvm_stat

The kvm_stat command is a python script which retrieves runtime statistics from the kvm kernel module. The kvm_stat command can be used to diagnose guest behavior visible to kvm. In particular, performance related issues with guests. Currently, the reported statistics are for the entire system; the behavior of all running guests is reported. To run this script you need to install the qemu-kvm-tools package. For more information, see Section 2.2, “Installing Virtualization Packages on an Existing Red Hat Enterprise Linux System”.
The kvm_stat command requires that the kvm kernel module is loaded and debugfs is mounted. If either of these features are not enabled, the command will output the required steps to enable debugfs or the kvm module. For example:
# kvm_stat
Please mount debugfs ('mount -t debugfs debugfs /sys/kernel/debug')
and ensure the kvm modules are loaded
Mount debugfs if required:
# mount -t debugfs debugfs /sys/kernel/debug
kvm_stat Output

The kvm_stat command outputs statistics for all guests and the host. The output is updated until the command is terminated (using Ctrl+c or the q key). Note that the output you see on your screen may differ. For an explanation of the output elements, click any of the terms to link to the defintion.

  # kvm_stat

  kvm statistics
   kvm_exit                      17724        66
    Individual exit reasons follow, see kvm_exit (NAME) for more information. 
   kvm_exit(CLGI)                    0         0
   kvm_exit(CPUID)                   0         0
   kvm_exit(CR0_SEL_WRITE)           0         0
   kvm_exit(EXCP_BASE)               0         0
   kvm_exit(FERR_FREEZE)             0         0
   kvm_exit(GDTR_READ)               0         0
   kvm_exit(GDTR_WRITE)              0         0
   kvm_exit(HLT)                    11        11
   kvm_exit(ICEBP)                   0         0
   kvm_exit(IDTR_READ)               0         0
   kvm_exit(IDTR_WRITE)              0         0
   kvm_exit(INIT)                    0         0
   kvm_exit(INTR)                    0         0
   kvm_exit(INVD)                    0         0
   kvm_exit(INVLPG)                  0         0
   kvm_exit(INVLPGA)                 0         0
   kvm_exit(IOIO)                    0         0
   kvm_exit(IRET)                    0         0
   kvm_exit(LDTR_READ)               0         0
   kvm_exit(LDTR_WRITE)              0         0
   kvm_exit(MONITOR)                 0         0
   kvm_exit(MSR)                    40        40
   kvm_exit(MWAIT)                   0         0
   kvm_exit(MWAIT_COND)              0         0
   kvm_exit(NMI)                     0         0
   kvm_exit(NPF)                     0         0
   kvm_exit(PAUSE)                   0         0
   kvm_exit(POPF)                    0         0
   kvm_exit(PUSHF)                   0         0
   kvm_exit(RDPMC)                   0         0
   kvm_exit(RDTSC)                   0         0
   kvm_exit(RDTSCP)                  0         0
   kvm_exit(READ_CR0)                0         0
   kvm_exit(READ_CR3)                0         0
   kvm_exit(READ_CR4)                0         0
   kvm_exit(READ_CR8)                0         0
   kvm_exit(READ_DR0)                0         0
   kvm_exit(READ_DR1)                0         0
   kvm_exit(READ_DR2)                0         0
   kvm_exit(READ_DR3)                0         0
   kvm_exit(READ_DR4)                0         0
   kvm_exit(READ_DR5)                0         0
   kvm_exit(READ_DR6)                0         0
   kvm_exit(READ_DR7)                0         0
   kvm_exit(RSM)                     0         0
   kvm_exit(SHUTDOWN)                0         0
   kvm_exit(SKINIT)                  0         0
   kvm_exit(SMI)                     0         0
   kvm_exit(STGI)                    0         0
   kvm_exit(SWINT)                   0         0
   kvm_exit(TASK_SWITCH)             0         0
   kvm_exit(TR_READ)                 0         0
   kvm_exit(TR_WRITE)                0         0
   kvm_exit(VINTR)                   1         1
   kvm_exit(VMLOAD)                  0         0
   kvm_exit(VMMCALL)                 0         0
   kvm_exit(VMRUN)                   0         0
   kvm_exit(VMSAVE)                  0         0
   kvm_exit(WBINVD)                  0         0
   kvm_exit(WRITE_CR0)               2         2
   kvm_exit(WRITE_CR3)               0         0
   kvm_exit(WRITE_CR4)               0         0
   kvm_exit(WRITE_CR8)               0         0
   kvm_exit(WRITE_DR0)               0         0
   kvm_exit(WRITE_DR1)               0         0
   kvm_exit(WRITE_DR2)               0         0
   kvm_exit(WRITE_DR3)               0         0
   kvm_exit(WRITE_DR4)               0         0
   kvm_exit(WRITE_DR5)               0         0
   kvm_exit(WRITE_DR6)               0         0
   kvm_exit(WRITE_DR7)               0         0
   kvm_entry                     17724        66
   kvm_apic                      13935        51
   kvm_emulate_insn              13924        51
   kvm_mmio                      13897        50
   varl-kvm_eoi                   3222        12
   kvm_inj_virq                   3222        12
   kvm_apic_accept_irq            3222        12
   kvm_pv_eoi                     3184        12
   kvm_fpu                         376         2
   kvm_cr                          177         1
   kvm_apic_ipi                    278         1
   kvm_msi_set_irq                 295         0
   kvm_pio                          79         0
   kvm_userspace_exit               52         0
   kvm_set_irq                      50         0
   kvm_pic_set_irq                  50         0
   kvm_ioapic_set_irq               50         0
   kvm_ack_irq                      25         0
   kvm_cpuid                        90         0
   kvm_msr                          12         0

Explanation of variables:

  • kvm_ack_irq - Number of interrupt controller (PIC/IOAPIC) interrupt acknowledgements.
  • kvm_age_page - Number of page age iterations by memory management unit (MMU) notifiers.
  • kvm_apic - Number of APIC register accesses.
  • kvm_apic_accept_irq - Number of interrupts accepted into local APIC.
  • kvm_apic_ipi - Number of inter processor interrupts.
  • kvm_async_pf_completed - Number of completions of asynchronous page faults.
  • kvm_async_pf_doublefault - Number of asynchronous page fault halts.
  • kvm_async_pf_not_present - Number of initializations of asynchronous page faults.
  • kvm_async_pf_ready - Number of completions of asynchronous page faults.
  • kvm_cpuid - Number of CPUID instructions executed.
  • kvm_cr - Number of trapped and emulated control register (CR) accesses (CR0, CR3, CR4, CR8).
  • kvm_emulate_insn - Number of emulated instructions.
  • kvm_entry - Number of emulated instructions.
  • kvm_eoi - Number of Advanced Programmable Interrupt Controller (APIC) end of interrupt (EOI) notifications.
  • kvm_exit - Number of VM-exits.
  • kvm_exit (NAME) - Individual exits that are processor-specific. See your processor's documentation for more information.
  • kvm_fpu - Number of KVM floating-point units (FPU) reloads.
  • kvm_hv_hypercall - Number of Hyper-V hypercalls.
  • kvm_hypercall - Number of non-Hyper-V hypercalls.
  • kvm_inj_exception - Number of exceptions injected into guest.
  • kvm_inj_virq - Number of interrupts injected into guest.
  • kvm_invlpga - Number of INVLPGA instructions intercepted.
  • kvm_ioapic_set_irq - Number of interrupts level changes to the virtual IOAPIC controller.
  • kvm_mmio - Number of emulated memory-mapped I/O (MMIO) operations.
  • kvm_msi_set_irq - Number of message-signaled interrupts (MSI).
  • kvm_msr - Number of model-specific register (MSR) accesses.
  • kvm_nested_intercepts - Number of L1 ⇒ L2 nested SVM switches.
  • kvm_nested_vmrun - Number of L1 ⇒ L2 nested SVM switches.
  • kvm_nested_intr_vmexit - Number of nested VM-exit injections due to interrupt window.
  • kvm_nested_vmexit - Exits to hypervisor while executing nested (L2) guest.
  • kvm_nested_vmexit_inject - Number of L2 ⇒ L1 nested switches.
  • kvm_page_fault - Number of page faults handled by hypervisor.
  • kvm_pic_set_irq - Number of interrupts level changes to the virtual programmable interrupt controller (PIC).
  • kvm_pio - Number of emulated programmed I/O (PIO) operations.
  • kvm_pv_eoi - Number of paravirtual end of input (EOI) events.
  • kvm_set_irq - Number of interrupt level changes at the generic IRQ controller level (counts PIC, IOAPIC and MSI).
  • kvm_skinit - Number of SVM SKINIT exits.
  • kvm_track_tsc - Number of time stamp counter (TSC) writes.
  • kvm_try_async_get_page - Number of asynchronous page fault attempts.
  • kvm_update_master_clock - Number of pvclock masterclock updates.
  • kvm_userspace_exit - Number of exits to user space.
  • kvm_write_tsc_offset - Number of TSC offset writes.
  • vcpu_match_mmio - Number of SPTE cached memory-mapped I/O (MMIO) hits.
The output information from the kvm_stat command is exported by the KVM hypervisor as pseudo files which are located in the /sys/kernel/debug/tracing/events/kvm/ directory.