Re: KVM got slow after adding more physical memory to host

Avi Kivity
2011-09-06T16:06:59Z

On 09/06/2011 07:06 PM, Avi Kivity wrote:
> On 09/06/2011 07:01 PM, Nikola Ciprich wrote:
>> > 404
>> ouch, dumb me :-/
>> http://nelide.cz/downloads/nik/trace.dat.bz2
>> sorry
>> n.
>>
>
> qemu-kvm-4618 [000] 13698.803169: kvm_emulate_insn:
> 0:806edb12: rep outsw
> qemu-kvm-4618 [000] 13698.803170: kvm_pio:
> pio_write at 0x1f0 size 2 count 1
> qemu-kvm-4618 [000] 13698.803171: kvm_userspace_exit:
> reason KVM_EXIT_IO (2)
> qemu-kvm-4618 [000] 13698.803186: kvm_entry: vcpu 0
> qemu-kvm-4618 [000] 13698.803189: kvm_exit:
> reason IO_INSTRUCTION rip 0x806edb12 info 1f00031 0
>
> qemu-kvm-4618 [000] 13698.803191: kvm_emulate_insn:
> 0:806edb12: rep outsw
> qemu-kvm-4618 [000] 13698.803192: kvm_pio:
> pio_write at 0x1f0 size 2 count 1
> qemu-kvm-4618 [000] 13698.803193: kvm_userspace_exit:
> reason KVM_EXIT_IO (2)
> qemu-kvm-4618 [000] 13698.803195: kvm_entry: vcpu 0
> qemu-kvm-4618 [000] 13698.803198: kvm_exit:
> reason IO_INSTRUCTION rip 0x806edb12 info 1f00031 0
>
>
> One of your guests is using IDE PIO instead of DMA. Switch it back to
> DMA.

Even better, switch it to virtio.

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