LCA: Catching up with X.org [LWN.net]

LCA: Catching up with X.org

Posted Jan 24, 2009 0:18 UTC (Sat) by jwb (guest, #15467)
Parent article: LCA: Catching up with X.org

"All told, it is a much cleaner and better-performing solution than its predecessors."

I object to the introduction of facts not in evidence. I haven't heard anyone claim that Intel + GEM graphics performance is better than the way it was before. My experience and the experience of pretty much every user posting to the xorg mailing list is that the latest bits are a noticeable regression. The problem is finding what caused the regression. Is UXA worse than EXA? Are they both worse than XAA? Is GEM busted? Nobody can tell.

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LCA: Catching up with X.org

Posted Jan 24, 2009 0:37 UTC (Sat) by nix (subscriber, #2304) [Link]

Text scrolling performance in X.org 1.5 is intolerably awful, I know that
(we're talking five seconds of 100% CPU consumption by X on an Athlon IV
to repaint the screen just once).

As soon as I figure out how to get sysprof to report backtraces inside X
with other than ?, I'll report it...

LCA: Catching up with X.org

Posted Jan 25, 2009 23:32 UTC (Sun) by jlokier (guest, #52227) [Link]

Sounds like a configuration error - using software scrolling (no acceleration) and not using a shadow framebuffer. That results in a lot of reads from video memory to the CPU (not GPU), which is often that sort of very slow.

Try enabling some kind of acceleration at least :-)
If you can't, perhaps you're using the "vesa" driver, in which case try enabling the shadow framebuffer.

This isn't new to Xorg 1.5, but maybe it configures itself differently and gets this wrong.

LCA: Catching up with X.org

Posted Jan 29, 2009 11:52 UTC (Thu) by nix (subscriber, #2304) [Link]

It's slow both with XAA and EXA, both of which should surely be accelerating. xterms forced to use core fonts scroll *fast*. Everything else is as fast as usual as well.

I wonder if render acceleration has been broken in recent versions of the ATI driver and/or x11-xserver 1.5... it's something that was only ever implemented for r200 cards anyway, so it could have been broken without most people noticing.

LCA: Catching up with X.org

Posted Feb 5, 2009 0:30 UTC (Thu) by nix (subscriber, #2304) [Link]

Fixed! The X-server-to-be, 1.6, is blindingly fast at client-side font
scrolling: client-side fonts, even antialiased ones, are very nearly as
fast as core fonts in 1.5. The glyph cache in 1.6 is excellent.