Re: [Qemu-devel] [PATCHv2] [RFC 6/7] aio / timers: Switch to ppoll, run AioContext timers in aio_poll/aio_dispatch

[Alex Bligh]

Stefan,

--On 25 July 2013 11:33:43 +0200 Stefan Hajnoczi <address@hidden> wrote:

> >      assert(progress || busy);
> > -    return true;
> > +    return progress;
>
> Now aio_poll() can return false when it used to return true?

I don't think that's a bug.

Firstly, this is the same thing you fixed and we discussed on another
thread.

Secondly, aio_poll always could return false. With the post patch line
numbering, here:

   233     /* No AIO operations?  Get us out of here */
   234     if (!busy) {
   235         return progress;
   236     }

The only circumstance where it now return false when previously it would
have exited at the bottom of aio_poll and returned true is if g_poll returns
such that aio_dispatch does nothing. That requires there to be no
aio_dispatch to the normal FD handlers (which would generally mean a
timeout) AND no timers running. This might happen if there was zero timeout.

--
Alex Bligh