Il 12/03/2012 16:25, Zhi Yong Wu ha scritto:
> > > - qemu_aio_flush();
> > > + QTAILQ_FOREACH(bs, &bdrv_states, list) {
> > > + do {
> > > + qemu_co_queue_restart_all(&bs->throttled_reqs);
> > > + qemu_aio_flush();
> > > + } while (!qemu_co_queue_empty(&bs->throttled_reqs));
> > > + }
> >
> > Even this is not enough. Block device 2 could start a throttled request
> > on block device 1.
>
> I think that this should be allowed here. It does not affect the final
> result. All throttled requests for all disks are drained.
Unfortunately, that depends on the order of block devices. It needs to
be something like this:
do {
qemu_aio_flush();
busy = false;
QTAILQ_FOREACH(bs, &bdrv_states, list) {
if (!qemu_co_queue_empty(&bs->throttled_reqs)) {
qemu_co_queue_restart_all(&bs->throttled_reqs);
busy = true;
}
}
} while (busy);
This means that bdrv_drain() cannot be implemented. The device models
can "drain themselves", but for example monitor commands must still rely
on bdrv_drain_all().
Paolo
