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drrossum

Member

From: Chicago

Registered: 2009-02-24

Posts: 83

slow refresh in urxvt with radeon KMS PageFlipping

On my system urxvt page refreshes were painfully slow. This occured for example when doing less on a file and moving the view up/down.
With xterm, things were fast, but I dispense with urxvt's automatic line rewrap and other features...

Slimming down urxvt with the --disable-all option didn't help.

It turned out that setting '"EnablePageFlip" "false"' in /etc/X11/xorg.conf.d/20-radeon.conf resolved the issue.

This was on my good old IBM T43p with an ATI r300 series chip.

Is this a bug in the radeon KMS driver?

I hope this may help other users with old radeon graphics...

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Taimon

Member

Registered: 2009-11-17

Posts: 5

Re: slow refresh in urxvt with radeon KMS PageFlipping

I'm having a similar problem with an ATI RV730 chip (AGP version). The page refresh in urxvt is much slow than in xterm.
However, disabling the page flipping had no effect. The problem is gone when I force Xorg to use the vesa driver.

No idea on how to debug this. Any help would be welcome.

Last edited by Taimon (2011-11-04 13:32:24)

drrossum

Member

From: Chicago

Registered: 2009-02-24

Posts: 83

Re: slow refresh in urxvt with radeon KMS PageFlipping

Did you load the agp modules for your chipset? You can search the syslog for 'agp' and 'radeon' related messages.

Did you try to boot without kms? I never had speed problems with urxvt under ums.

Are you using xft fonts?  I am, and I don't want to compromise on that.  I think turning of the antialias can give a little speed improvement too.  My .Xdefaults font line reads:
urxvt*font : xft:Terminus:pixelsize=14:antialias=false

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Taimon

Member

Registered: 2009-11-17

Posts: 5

Re: slow refresh in urxvt with radeon KMS PageFlipping

Did you load the agp modules for your chipset? You can search the syslog for 'agp' and 'radeon' related messages.

I'm not sure if the chipset needs a special agp module. I configured mkinitcpio to first load intel_agp and then radeon.

Did you try to boot without kms? I never had speed problems with urxvt under ums.

Indeed, there are no problems under ums.
I didn't notice at first but some other applications had "performance problems" as well. For example, applications that use the SDL library.

/Edit:
I ran gtkperf under KMS and UMS and the line drawing test was considerably slower under KMS. (23s vs. 4s)

Are you using xft fonts?

Nope, at least I think I don't. 

URxvt.font:             -*-fixed-medium-r-semicondensed-*-13-*-*-*-*-*-iso10646-*

Last edited by Taimon (2011-11-05 10:02:16)