Re: [Qemu-devel] [PATCH 0/3] *** make netlayer re-entrant ***

[Stefan Hajnoczi]

On Thu, Mar 07, 2013 at 10:06:52AM +0800, liu ping fan wrote:
> On Wed, Mar 6, 2013 at 5:30 AM, mdroth <address@hidden> wrote:
> > On Sun, Mar 03, 2013 at 09:21:19PM +0800, Liu Ping Fan wrote:
> >> From: Liu Ping Fan <address@hidden>
> >>
> >> This series aim to make netlayer re-entrant, so netlayer can
> >> run out of biglock safely.
> >
> > I think most of the locking considerations are still applicable either
> > way, but this series seems to be written under the assumption that
> > we'll be associating hubs/ports with separate AioContexts to facilitate
> > driving the event handling outside of the iothread. Is this the case?
> >
> Yes.
> > From what I gathered from the other thread, the path forward was to
> > replace the global iohandler list that we currently use to drive
> > NetClient events and replace it with a GSource and GMainContext, rather
> > than relying on AioContexts.
> >
> Not quite sure about it. Seems that AioContext is built on GSource, so
> I think they are similar, and AioContext is easy to reuse.
> 
> > I do agree that the event handlers currently grouped under
> > iohandler.c:io_handlers look like a nice fit for AioContexts, but other
> > things like slirp and chardevs seem better served by a more general
> > mechanism like GSources/GMainContexts. The chardev flow control patches
> > seem to be doing something similar already as well.
> >
> I have made some fix for this series, apart from the concert about
> GSource/ AioContext.  Hope to discuss it clearly in next version and
> fix it too. BTW what can we benefit from AioContext besides those from
> GSource

One thing I forgot to add: net/ doesn't use BH or
qemu_aio_set_fd_handler() so AioContext isn't strictly necessary.

Stefan