Re: [Qemu-devel] [PATCH RFC] iothread: Add "spawns" property

[Fam Zheng]

On Fri, 11/04 11:03, Daniel P. Berrange wrote:
> On Fri, Nov 04, 2016 at 10:58:04AM +0000, Stefan Hajnoczi wrote:
> > On Wed, Oct 19, 2016 at 04:04:50PM +0800, Fam Zheng wrote:
> > > The option specifies how many threads to spawn under the iothread
> > > object. All threads share the same AioContext so they can safely run
> > > (contend) together.
> > > 
> > > With AioContext going away, the spawns will natually enable the block
> > > multi-queue work.
> > > 
> > > Signed-off-by: Fam Zheng <address@hidden>
> > > 
> > > ---
> > > 
> > > Based on v2 of Paolo's RFifoLock removal series, with which the
> > > symmetric contention on the single AioContext is no longer a busy
> > > preempt loop.
> > > ---
> > >  include/sysemu/iothread.h |  19 ++++--
> > >  iothread.c                | 148 
> > > ++++++++++++++++++++++++++++++++++------------
> > >  2 files changed, 125 insertions(+), 42 deletions(-)
> > 
> > I'm not happy with "IOThread" becoming a group of threads.  IOThread
> > should stay the way it is.  Instead you should add a new object type
> > that simply groups IOThreads for convenient assignment to devices, e.g.
> > IOThreadGroup.  Then multiqueue devices can use an IOThreadGroup to work
> > inside multiple IOThreads.
> 
> Do we even need a IOThreadGroup object ? Can't we just explicitly pass
> a list of IOThread object IDs to the device. eg something like
> 
>    -device virtio-blk-pci,iothread=t1,iothread=t2,iothread=t3

Is that a supported syntax by qdev/QOM?

Fam