wido opened a new issue #4883:
URL: https://github.com/apache/cloudstack/issues/4883
##### ISSUE TYPE
* Feature Idea
##### COMPONENT NAME
~~~
KVM
~~~
##### CLOUDSTACK VERSION
~~~
master
~~~
##### SUMMARY
~~~
ouring is a new kernel asynchronous I/O processing mechanism proposed as a
much faster alternative for conventional Linux AIO. Patches were merged in
Linux 5.1 and gave a promised performance boost. We decided to integrate it
into QEMU to make virtualized storage devices work more efficiently. Let's take
a look at how iouring works in QEMU.
~~~
Source:
-
https://www.phoronix.com/scan.php?page=news_item&px=KVM-IO-uring-Passthrough-LF2020
- https://archive.fosdem.org/2020/schedule/event/vai_io_uring_in_qemu/
By using io_uring with Qemu we can see a massive I/O performance improvement
within Virtual Machines running from Local and/or NFS storage.
In order to use this we need:
- Qemu >= 5.0
- Libvirt >= 6.3.0
We then need to add this to the XML definition for libvirt which would then
look like:
~~~
<disk type='file' device='disk'>
<driver name='qemu' type='qcow2' cache='writeback' discard='unmap'
io='io_uring'/>
<source
file='/var/lib/libvirt/images/a0f677c6-b065-4795-b468-2b5974496c75'/>
<backingStore/>
<target dev='sda' bus='scsi'/>
<serial>a0f677c6b0654795b468</serial>
<alias name='scsi0-0-0-0'/>
<address type='drive' controller='0' bus='0' target='0' unit='0'/>
</disk>
~~~
With io_uring I/O performance can improve drastically and reach near
bare-metal performance.
Currently there is no Qemu version in a stable Ubuntu nor CentOS release,
but we can already merge this in master so that when this is released we can
use it.
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