EXA

[Rui Tiago Cação Matos]

On Dom, 2007-08-05 at 20:01 +0200, Lukas Hejtmanek wrote:
> OK, sounds great! However, one politically incorrect question, what does need
> to be done to have EXA at the same speed as XAA? I still have to use XAA
> because EXA is much slower (i915 chipset).

Yea, I feel like adding fuel to this fire today.

2D X performance in general has always been sub par in my experience.
Especially when compared to Windows (I'm thinking XP here, but any other
really) applications. Repaints feel slow, scrolling feels jerky etc.[1]

I do understand that there are a ton of variables playing here all the
way from the kernel to X (including drivers and lack of hardware
knowledge), to toolkits, to apps [not] being smart etc. Tools for
measuring things are laking generally in Linux too.

OK but enough whining. I'm attaching 2 sysprof profiles I did of 2
actions I perform regularly which show the X server as the bottleneck:

1. is text scrolling on a gnome-terminal.
2. is scrolling some web pages (not all) on firefox. This one is [2].

These profiles were performed on a MacMini (intel 945GM) with Fedora 7
running

* xorg-x11-server 1.3.0.0-9.fc7
* intel driver commit 45962eed51120ff77326c29d72cf8b6cd8a934b5
(2007-07-23)
* xcompmgr -a (which sometimes displays garbage...)

The first issue I think is what Carl Worth mentioned on his last blog
entry[3] and the second is probably also firefox's fault (which *is*
slower on Linux than on Windows or OS X).

All this said, I'd like to thank all the people that put hard work into
freedesktop and Intel for playing nice with FOSS[4].

Rui

[1] If at this point you are going to blame the toolkit and not X,
remember: comparing pure Xlib apps performance with standard Windows
apps is bogus since the visual richness is orders of magnitude apart as
well as the API abstraction level.

[2] http://oprofile.sourceforge.net/news/

[3] http://cworth.org/exa/storing_glyphs_as_pixmaps/

[4] Hey, I'm making my buying decisions based on this!

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