Re: Speed improvement of gnome-terminal

[Alexander Larsson <alexl redhat com>]

On Thu, 2004-10-14 at 09:41 -0400, Dave Ahlswede wrote:
> On Thu, 2004-10-14 at 15:21 +0200, Alexander Larsson wrote:
> > Pango is used very little in vte. I think at this point the major
> > slowdown in gnome-terminal is rendering the text. If you pick a bitmap
> > font its a lot faster. If someone wants to optimize this they need to
> > work on the Xserver level to make Xrender faster. Latest Xorg version
> > already has some optimizations in this area.
> 
> I don't think that's entirely it.. rxvt-unicode has similar capabilities
> to Gnome-terminal (Xft fonts, unicode support, automatic
> font-switching), and for some reason or another renders text much
> faster. 
> 
> This can be observed by catting a large text file (One that would take
> several seconds to completely print), and observing a CPU monitor--
> Gnome-terminal causes the CPU usage to go up appreciably higher than
> rxvt-unicode's. (On my system, gnome-terminal measures about 40% usage,
> while rxvt measures in at about 13%). This is with the same Xft font,
> fully antialiased.
> 
> So I think there's definitely a possibility for some sort of speedup in
> the rendering somewhere.

Maybe rxvt delays longer before drawing? This kind of thing always needs
some balancing. To maximize throughput in the case of the cat one should
avoid actually drawing anything until the whole file has scrolled by. To
maximize your ability to see what rushes by you should draw and scroll
each line separately. Both extremes are clearly bad, the best way is
somewhere inbetween, but its not obvious exactly where.

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 Alexander Larsson                                            Red Hat, Inc 
                   alexl redhat com    alla lysator liu se 
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