Hello!

 

I want to make patch for exposing min_io_size and opt_io_size properties to

export block topology information to the guest. This is needed to set optimal

i/o alignment for storages in underlay.

 

This option already exists in qemu but haven't been implemented yet in libvirt.

 

It is assumed if you do not set these values qemu wont be report that into

the guest. Inside guest undefined opt_io_size value transferred to

sys/block/{drive}/queue/optimal_io_size like 0. And filesystems like xfs or

ext4 don't set correct aggregated io size (typicaly 32k bytes for xfs).

 

At the moment i think to make a patch with changes to the conf and qemu parts

of libvirt.

 

These options should be added to the address tag in the guest xml to section

for disk devices. The values should be positive integers. To use these options,

you must use qemu.

 

Can you tell me if there are any additional restrictions about this options

that should be taken into account?