[dm-devel] Re: [kvm-devel] I/O bandwidth control on KVM

[Ryo Tsuruta <ryov valinux co jp>]

Hi,

> If you are using virtio drivers in the guest (which I presume you are given the reference to /dev/vda), try using the following -drive syntax:
>
> -drive file=/dev/mapper/ioband1,if=virtio,boot=on,cache=off
>
> This will force the use of O_DIRECT.  By default, QEMU does not open with O_DIRECT so you'll see page cache effects.

Thank you for your suggestion.
I was using virtio drives as you wrote.
I just thought that kvm would use O_DIRECT option when applications on
the guest opened files with O_DIRECT option.
I'll try the way you mentioned and report back.

Thanks,
Ryo Tsuruta