Re: Scrolling performance

On Tue, 20 Jun 2006 22:21:16 +0200, Clemens Eisserer said:

> 1.) Not even one comment from a developer. Maybe there are not enough,
> maybe nobody cares, ore maybe they can't cope with critic? I don't
> know.

Maybe none of the developers are seeing your issue, and none of the usual
bleeding-edge testers see it either.  This makes it hard for them to fix it.

> 2.) Some fans respond that on their machines its working fast enough.

I'm suspecting you're addressing me with that comment. ;)

My point was that it *isn't* the case where every single GTK2 system is
seeing horrid performance, and that it always sucks in every case.  You
seem to be encountering an issue that is *not* present on every system.

(On the other hand, if computers and users didn't keep finding new ways
to trip over obscure corner cases, I'd be unemployed, so I'm not complaining ;)

> I see/saw quite frequently complaints about GTK's performance, I saw
> tables comparing GTK-1.2 vs. GTK-2 performance, authors migrating away
> from GTK-2 because they were concerned loosing users when switching to
> this toolkit.

Because usually the person complaining disappears before providing useful
info like this:

> > So where *does* the time go to, if not pango?  The more detail you can
> > provide, the easier it is to track down.
> I did some sysprof testing back when I tried to analyze why the
> Eclipse/GTK port performs like crap (this was FC4 / GTK-2.6 / Default
> theme). It was almost a flat profile, but X spiked quite a lot. Doing
> the same test (invalidating eclispe's main window) shows about half
> (!!!) of the time is spent in X. The test with gftp (moving splitters)
> shows X using 67.1% of CPU whereas gftp itself only consumes 31%.
> I am using Xorg 6.9 with grayscale-aa fonts (xrender is accalerated).

OK, *now* we have something that we can start looking into - we now know
that at least part of the problem is that gftp is generating some very
sub-optimal X requests.  And we have a test case that reproduces easily
(although on my box moving the main horizontal splitter in the gftp gui
up and down result in about 70% gftp-gtk and 25% in the X server).

I'll take a closer look at this later tonight - the kernel I have booted at the
moment doesn't have oprofile support.

(And no, I don't pretend to know the GTK innards well enough to fix this,
but I've been doing systems debugging and tuning for enough decades that I
certainly should be able to get a clear and coherent bugzilla out of it
so that somebody else can run with it from there...)

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