Re: linux-aio usable?

Avi Kivity
2010-03-08T09:10:46Z

On 03/08/2010 03:46 AM, Bernhard Schmidt wrote:
> Hi,
>
> sorry for this pretty generic question, I did not find any real pros and
> cons on the net anywhere, but I might just have missed them.
>
> In a pure x86_64 environment (~2.6.32 vanilla kernel, 0.12.3 qemu-kvm),
> is enabling linux-aio in KVM a good idea?

Yes.

> What are the
> advantages/disadvantages?

It's faster.

> Are there any potential pitfalls?
>

It won't work well unless running on a block device (partition or LVM).

> The reason I'm asking is that there has been some traffic on the list
> about it, so it seems to be something people want to get working.
> qemu-kvm in Ubuntu Lucid is currently not compiled with that option.
> I've made a local version with aio and it seems to work fine (and
> performs a bit better at first glance).
>
> Is there any reason one should not compile that feature by default?
>

Not to my knowledge.

> Does it do anything if not explicitly run with aio=native?
>

IIUC, no.

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