Re: gobject-performance

On Fri, Sep 25, 2009 at 1:16 AM, A. Walton <awalton gnome org> wrote:
> Just have a small question on the subject: has anyone performed any
> library or application benchmarks to see how much this means in the
> real world and not just for the threaded microbenchmarks that you
> wrote? The non-threaded speedups are pretty impressive on their own,
> but it'd be nice to see what we could expect from e.g. GStreamer with
> these changes applied.
The motivations for the patches have in all cases been real world
problems, though I never explicitly benchmarked the effects
afterwards, as I was happy just looking at my microbenchmarks.

The work on lockless O(1) interface lookups was motivated by trying to
sort a huge treeview and getting a huge overhead from it. I just
tested my simple liststore script again (attached here), and sorting
the numbers column on that liststore is roughly 25% faster now. So I'd
expect you to see these improvements in multithreaded apps that sort
huge treeviews: file chooser and nautilus with lots of files, probably
evolution in huge dirs.

Speeding up g_type_class_ref() was not motivated by code that's
already out in the wild, but by the desire to make ever smaller
objects into real objects, that is currently not feasible due to this
overhead. Examples here are an mpegps (mpegts?) parser the GStreamer
guys had been working on, that was having 70% overhead just creating
lots of small GstBuffers, Philip Van Hoof's work on Iterable
interfaces or Vala automatically making a GObject out of Vala classes.
So no real code I can point you at, but definitely a huge demand.

The big problem with "show me real-life benchmarks" type questions is
that developers usually work around visible limitations in lower
layers, so you cannot see any immediate results. Instead, developers
can - if they realize the limitations are gone - get rid of their
workarounds or use features that previously just didn't work. And then
people can get rid of APIs like for example g_type_class_peek_static()
(for g_type_class_ref()), ETable (for GtkTreeView) or libgstvideo (for


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