Re: [Qemu-devel] question about concurrent block job

[Stefan Hajnoczi]

On Wed, Apr 24, 2013 at 12:28 PM, Zhangleiqiang
<address@hidden> wrote:
>         I found qemu does not support concurrently running multiple block 
> jobs of the same drive (limited by the bs->in_use field).  But there are 
> indeed some type of block job can run concurrently, such as running block 
> stream job while running drive mirror, etc.  Am I right ? Is it necessary to 
> introduce the concurrency mechanism in qemu ?

stream and mirror both switch to the destination image file when they
complete.  I'm not sure it makes sense to run both at the same time.
Some of the block jobs can interfere with each other, so it's simplest
to only allow one.

Enabling multiple jobs at the same time will require a lot of care,
including extending the HMP/QMP APIs to deal with multiple jobs.
bs->job is a scalar field at the moment.

Stefan