[Qemu-devel] Re: [PATCH v6 18/18] virtio-serial-bus: wake up iothread upon guest read notification

[Anthony Liguori]

On 04/28/2010 02:29 AM, Amit Shah wrote:
> On (Tue) Apr 27 2010 [12:41:27], Anthony Liguori wrote:
>    
> > On 04/27/2010 07:34 AM, Amit Shah wrote:
> >      
> > > From: Marcelo Tosatti<address@hidden>
> > >
> > > Wake up iothread when buffers are consumed.
> > >
> > > Signed-off-by: Marcelo Tosatti<address@hidden>
> > > Signed-off-by: Amit Shah<address@hidden>
> > >
> > >        
> > What's the race here?  This looks very odd to me.
> >      
> When the guest indicates it has added buffers to the vq, the iothread
> can then start consuming them. Without this notification, the iothread
> only polls for free buffers when it times out or gets woken up
> otherwise.
>    

When you say, polls for free buffers, what do you mean by that?

You mean, there's a can_read() somewhere that checks for free buffers?

I think switching to qemu_set_fd_handler() would be a better solution.

Regards,

Anthony Liguori

> Other virtio devices do it similarly as well.
>
>                 Amit
>