Re: Adding synchronization to the WM spec

[Owen Taylor <otaylor redhat com>]

On Tue, 2011-11-01 at 08:15 +0100, Martin Gräßlin wrote:
> On Saturday 29 October 2011 12:29:14 Owen Taylor wrote:
> > There are quite a few outstanding issues related to synchronization
> > between applications and the compositor. We want the compositor
> > to avoid drawing a window when it is only half done with an update,
> > we want to throttle the drawing rate in the application, and we
> > need to incorporate NVIDIA's fence sync objects if we want to get
> > composited drawing correct with their driver.
> > 
> > This update to the window manager specification attempts to address
> > these needs in a unified way. What I'm basically proposing here is:
> great work. I am all for it and we will add support for it in KWin. 
> Unfortunately you proposed it two days too late for inclusion in 4.8.

Sorry about that - definitely not intentional. I think it's going to
take a little while to finalize anyways. I wanted to get a proposal out
for the spec early, but I certainly haven't finished everything I'd want
to do to make sure that things are working properly.

> Do you have any example clients implementing the client side. If yes it would 
> be great if you could share it somewhere in a git repository, so that we can 
> easily test the implementation in the window manager.

xcompbench - http://git.fishsoup.net/cgit/xcompbench - supports an
earlier version of the protocol. (The main difference I can think of is
that it uses _NET_WM_FRAME_DRAWN instead of _NET_WM_SYNC_DRAWN.) I'll be
updating it to the current version and adding fencing as I continue the
work.

- Owen