[kata-dev] [Announce] virtio-fs released with Kata Containers support

Qixuan Wu qixuan.wu at linux.alibaba.com
Thu Dec 20 02:36:59 UTC 2018

On 2018/12/17 下午10:27, Stefan Hajnoczi Wrote:
> On Sun, Dec 16, 2018 at 09:09:48AM +0800, Qixuan Wu wrote:
>> 1) Did you compare the performance to the virtio-blk raw or qcow2 solution
>> of normal virtual machine?
> Not yet.
> Guest and host page cache performance can dominate benchmarks, so we
> typically use fio direct=1 with QEMU -drive cache=none (O_DIRECT) to
> focus purely on disk I/O performance and not page cache.  The same thing
> can be done with virtio-fs so that every I/O operation requires
> communication with the host.  In theory virtio-fs should be comparable
> to virtio-blk on raw.
> In real-world scenarios the page cache will be enabled, especially for
> the virtio-fs DAX feature.  So I need to think carefully about what to
> benchmark, but it will probably include both configurations.

Thank you for your reply. Hope to see the data with virtio-blk later.

>> 2) Whether does it impact live-migration of guest os ?
> Virtio-fs currently does not support live migration.  Is there a
> requirement for live migration with Kata Containers use cases?

Yes, currently it's not a common case, that maybe because kata container 
is not used in product so much. I think kata container is not only used 
for serverless scenario, also can be used by the application which has 
long lifecycle. If the physical host need reboot because of kernel bug 
or hardware bug, when kata container is running, live-migration is needed.

So for long lifecycle cloud application, live-migration case is always 
there. Because for cloud application, include runc container, kata 
container and fully virtual machine container, they don't care about 
which host is running. So host need reboot without disturbing cloud 

Qixuan Wu.

> Stefan

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