Re: [Qemu-devel] [RFC PATCH 0/4] aio: Don't poll ioeventfd in nested aio_poll()

[Fam Zheng]

On Thu, 05/28 13:19, Paolo Bonzini wrote:
> 
> 
> On 28/05/2015 13:16, Fam Zheng wrote:
> > > On 28/05/2015 03:46, Fam Zheng wrote:
> > > > The main context uses iohandler and aio_dispatch, neither calls
> > > > aio_set_dispatching(). However, if we have [2], they can be changed to
> > > > aio_poll(), then would this idea work?
> > > 
> > > I think it's a bad idea to handle aio_poll for context B in a different
> > > way, just because you have an outer aio_poll for context A...
> > 
> > But we already do something similar: ignoring slirp, main_loop_wait() is 
> > like
> > an iothread aio_poll() without the "outermost differentiation", while the
> > current aio_poll() in bdrv_drain() is roughly "main_loop_wait() minus
> > iohandlers".
> 
> Right, but the two sets of iohandlers are stored in different places, so
> it's obvious that you don't execute all of them.  On the other hand,
> examining global state in aio_poll is really bad.
> 

OK.

Would moving the ioeventfds to a new top level aio_loop_wait() be any better?
That way no global state is needed.

Fam