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Linux, BSD, Unix etc. - EXA accelerated X

kozz - Jan 11, 2006 - 17:40
Post subject: EXA accelerated X

I tried the extension Composite and Render the other day together with EXA enabled on the Pegasos. It was almost useable Smile

Just wanted to give a hint about that, it do look really good. Or well, it was indeed slower than "normal", specially when switching desktop and when having many windows at once. But it was a huge improvment from without EXA.

I was using Xorg 7.0.

To enable it you have to add the option

Code:

Option "AccelMethod" "exa"

in your Device section and then add a section

Code:

Section "Extensions"
Option "Composite" "Enable"
Option "Render" "Enable"
EndSection

to your /etc/X11/xorg.conf.

Trizt - Jan 11, 2006 - 18:50
Post subject: RE: EXA accelerated X

Did you try it without the composite/render extentions?

kozz - Jan 11, 2006 - 19:13
Post subject: RE: EXA accelerated X

Isn't EXA only to accelerate Render?

Trizt - Jan 11, 2006 - 19:22
Post subject: RE: EXA accelerated X

Not sure about that... noticed that I can't enable the render, it's nowadyas a part of the composite.

dholm - Jan 11, 2006 - 19:44
Post subject: RE: EXA accelerated X

No, it accelerates COMPOSITE as well. That's why ATi didn't want to add support for COMPOSITE since XAA would be deprecated by 7.0.

kozz - Jan 11, 2006 - 23:39
Post subject: RE: EXA accelerated X

Yes, you are right dholm. But anyway, shouldn't do any good to disable composite and render but enable exa. I do however wonder if anything else than transparent windows, shadows etc with help of tools like xcompmgr can get speedups from EXA and render/composite enabled.

mejde - Jan 12, 2006 - 01:10
Post subject: RE: EXA accelerated X

@kozz
The memory management (pixmap scoring and migration algorithms) still needs fine tuning, that's probably why it slows down when switching desktops etc. See eg:
http://lists.freedesktop.org/archives/xorg/2005-December/011549.html
http://lists.freedesktop.org/archives/xorg/2005-December/011816.html

@Trizt
The Render Extension is part of the Composite Extension? If that's what you meant it sounds... plain wrong... The Render Extension introduces the porter-duff image compositing model. The Composite Extension is used to render windows to off-screen buffers so that they later can be assembled by a Compositing manager (that at the same time can add some neat effects, like drop shadows). I don't see why one would be merged with the other. If you meant something else, ignore me.

@dholm
You're both right, in a way, but I think kozz is more right. Wink

EXA doesn't accelerate Composite per se, rather, most compositing managers use the Render Extension. XAA made Render acceleration hard, EXA makes it much easier.

http://wiki.x.org/wiki/XorgPerformance#head-f6001036c92c3cc8be770c9554f12ea95fc3c32b

Please correct me if I'm wrong... it happens far more often then I would like Wink

Trizt - Jan 12, 2006 - 02:45
Post subject: RE: EXA accelerated X

mejde wrote:

@kozz
The memory management (pixmap scoring and migration algorithms) still needs fine tuning, that's probably why it slows down when switching desktops etc.

I belive that the slowness comes from the use of xcompmgr, as I do use my PPC as server, I don't experiment with KDE3.5 on it, but from my expriences from x86 world, there is no need for xcompmgr. But of course making the algorithms better would speed up things.

mejde wrote:

@Trizt
The Render Extension is part of the Composite Extension? If that's what you meant it sounds... plain wrong...

I can just say what I have read in the Gentoo Transparency Howto and it says

Quote:

Note that contrary to what was previously stated here, Option "RENDER" "Enable" is not, and never has been needed. The Render extension has been enabled by default since it was integrated, and is what has allowed things like antialiased fonts.

And I belive they do have a case there as my Xorg does complain and exit if I add render option, but still I do get translucency to work fine without it.

mejde - Jan 12, 2006 - 16:46
Post subject: RE: EXA accelerated X

Enabled by default and merged with another extension are two completely different things. Wink

kozz - Jan 13, 2006 - 10:24
Post subject: RE: EXA accelerated X

Ok, but now I turned it off, is faster without these features.

And to Trizt, I tried to run X without render and composite enabled but with EXA enabled. And I actually found a difference. KMail became much slower, slower when showing the list of emails and when switching between different mails to update the content. You could actually see the text being redrawn, thats not the case without EXA enabled. Might be more differences, but that's what I noted. So now everything is off.

Trizt - Jan 13, 2006 - 10:27
Post subject: RE: EXA accelerated X

It's good to know.

mejde - Jan 13, 2006 - 21:04
Post subject: RE: EXA accelerated X

Disabling the Render Extension makes no sense whether you're running XAA or EXA. Most widget toolkits make heavy use of Render since many years back.

If the slowdowns in KMail are due to Render being disabled (was it really disabled?) or because of EXA, I don't know. If Render was enabled the slowdown is probably, just like the other slowdowns when switching desktops etc., due to the memory management (I asked at #xorg-devel... or perhaps you have found another bug?). The memory manager being less than good is a known problem and is being worked on.

It makes no sense that Render havey apps should be slower when running EXA than XAA with or without Composite running (not in a world with a better mm anyway). EXA is after all designed to make Render easy to accelerate.

kozz - Jan 14, 2006 - 12:09
Post subject: RE: EXA accelerated X

Yes I saw what they said in #xorg-devel. I'm sure it is ment to be better in all ways, but that is not probably the case yet. There are probably good reasons for EXA to be expermental and not enabled by default yet, but we will probably be there some day. Anyway, it was intresting to test and see what it felt like, will be really cool after some more work... and do not forget about Xglx Smile

but that is a still further away from being used for an ordninary desktop.