Re: [Qemu-devel] [PATCH 2/3] Always use nonblocking mode for qemu_chr_open_fd.

[Anthony Liguori]

Paul Brook wrote:
> On Wednesday 23 July 2008, Gerd Hoffmann wrote:
>   
> > Anthony Liguori wrote:
> >     
> > > Gerd Hoffmann wrote:
> > >       
> > > > Comments on this one?
> > > >         
> > > Checking every 100ms for every pty device really makes me cringe.
> > >       
> > Only when unconnected, and the interval can be changed.
> > And I'm certainly open for better ideas ...
> >     
>
> Anything that requires periodic polling is almost certainly wrong.
>
> If it's unconnected then why do we need to poll at all? If we're discarding 
> data then we aren't going to retry, so it should be sufficient to check 
> whenever we send data.
>   

There's no way to determine if someone reconnected without trying to do 
a read().  pty's just aren't designed for this sort of thing.

Regards,

Anthony Liguori

> Paul
>
>
>