Re: [Qemu-block] [PATCH v3] migration/block:limit the time used for block migration

[Stefan Hajnoczi]

On Sat, Apr 08, 2017 at 06:09:16PM +0800, Paolo Bonzini wrote:
> On 07/04/2017 19:33, Stefan Hajnoczi wrote:
> > The migration thread is holding the QEMU global mutex, the AioContext,
> > and the qcow2 s->lock while the L2 table is read from disk.
> > 
> > The QEMU global mutex is needed for block layer operations that touch
> > the global drives list.  bdrv_is_allocated() can be called without the
> > global mutex.
> 
> Hi Stefan,
> 
> only virtio-blk and virtio-scsi take the AioContext lock (because they
> support dataplane).  For block migration to work with devices such as
> IDE, it needs to take the iothread lock too.  I think there's a comment
> about this in migration/block.c.

Good point.  :(

Stefan

signature.asc
Description: PGP signature