Re: Some initial thoughts about 2.4

[Sander Vesik <sander_traveling yahoo co uk>]

 --- Owen Taylor <otaylor redhat com> wrote: > 
> But "Make GTK+ faster" shouldn't be on the 2.4 feature list because
> it doesn't actually indicate any particular action. There are
> various performance related improvements that can be done that
> I know of.
>  
>  - GObject could be made 20-30% faster by careful code optimization
>  - fontconfig startup times could be substantially improved
>    with some optimization
>  - Caching of scratch GC's inside GDK might improve things a bit,
>    though I've never seen evidence on profiles that GC creation
>    destruction is a major factor.
>  - There are some improvements that can be made to 
>    gdk_window_invalidate_region() (which shows up high on some
>    profiles)

gtk+ is presently also quite bad when it comes to locality of reference, 
the dTLB miss rate should preferably really come down by about half at 
least. This may (or may not) come down to smater allocation.

> 
> These are things that I've noted from spending weeks studying profiles
> of GTK+ and are generally reasonably major projects. The stuff that
> was easy to do and produced big improvements has been done.
> 
> I'd expect the overall improvement from implementing the above to 
> be order 10% ... I don't think it would be possible to make GTK+ 
> 50% faster without major feature removal. (Please prove me wrong ...) 
> 
> On the other hand, machines double in speed, both on the high and low
> end, every year or two, so GTK+ will be twice as fast soon enough.
> 

Machines double for speed for things that are nicely behaved in certain 
respects, gtk+ presently hits some snags and scales a bit worse than that. 
"Speed" is a relative thing that depends on the code at hand. 

> A lot of the easiest ways to improve GTK+ performance are outside
> of GTK+:
> 
>  - Implement object file reordering for Linux
>  - Work on optimization of RENDER inside the X server
> 

- improve tools that tell you what goes on inside the machine

> After the pixops improvements that have been in bugzilla for a 
> long time, if my interest was overall toolkit speed, these would
> be the areas I'd be looking at first.
> 
> Regards,
>                                         Owen


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