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



Avi Kivity wrote:
Anthony Liguori wrote:

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.


Good point.  But IIRC cache=off is not limited to virtio?

Nope. I just wanted to give the exact syntax to use and it looked like he was using virtio.

Regards,

Anthony Liguori


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