Re: [Qemu-block] RFC iscsi: set FUA and DPO if !bs->enable_write_cache

[Peter Lieven]

Am 14.04.2015 um 11:04 schrieb Stefan Hajnoczi:
> On Tue, Apr 14, 2015 at 7:49 AM, Peter Lieven <address@hidden> wrote:
> > Ronnie came up with an idea to reduce latency if !bs->enable_write_cache for
> > an iSCSI device.
> >
> > If !bs->enable_write_cache Qemu sends a flush after every single write. What
> > could be done is
> > the following:
> >
> > if (!bs->enable_write_cache)
> >   set FUA (force unit access) and DPO (disable page out) bits in every write
> > cmd
> >   make iscsi_co_flush a NOOP in this case.
> >
> > Your thoughts?
> Do other commands besides writes rely on iscsi_co_flush()?

That I was asking myself to. I cannot think of any currently. WRITESAME, of 
course, but
I would consider this as write.

Peter