Re: [gtk-vnc-devel] [PATCH 5/7] Use X window backing store for the VNC window 2008-11-24 Federico Mena Quintero <federico@novell.com>

[Hugh O. B. <hb...@re...>]

On Thu, Dec 18, 2008 at 08:17:55PM +0000, Daniel P. Berrange wrote:
> On Thu, Dec 18, 2008 at 10:08:25AM -0600, Federico Mena Quintero wrote:
> > On Wed, 2008-12-17 at 19:51 -0600, Anthony Liguori wrote:
> > 
> > [backing store]
> > > 
> > > Is this just double buffering in GTK parlance?  If you avoid disabling 
> > > double buffering, does that help?
> > 
> > Nope, it's different.  You can ask the X server to use backing store if
> > possible --- if the server can save the contents of a window, it can
> > avoid sending Expose events when the window is unobscured.  That is,
> > nothing goes over the wire in the ideal case.
> > 
> > [This is similar to requesting "save-unders" for temporary windows, but
> > it saves your actual contents, not the underlying contents.]
> 
> Ok, I see how this can make a big difference for slow X connections.
> Obviously it'll have a bit of a memory overhead in the X server
> to maintain the backing store. 
> 
> ACk to the patch in principle, once its has been #ifdef'd to not hardcode
> the use of GTK X backend on all platforms. 
> 
> Daniel

Glad to see this going in, it will be very heplful on the oVirt cloud
setup (slow console connections will be the rule rather than the
exception).

--Hugh