[Bug 30679] KDE editor sluggish from f8fb9312d791af1f77020e8c2d35bb30841ed9aa

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=30679

--- Comment #14 from Ignacio R. Morelle <shadowm at wesnoth.org> 2010-12-31 18:17:19 PST ---
I have just made a rather odd discovery using current master HEAD DDX, latest
Mesa from git master on Linux 2.6.37-rc8, X.org server 1.9.3 RC-2 from Debian
experimental (1.9.2.902).

The bitmap font I prefer for Konsole is Terminus, and it comes in a few fixed
sizes such as Regular 9, Regular & Bold 11, Regular & Bold 12. I used to run
Konsole using Terminus Bold 11 until a few days ago, when I figured out that it
messed up the TrueType fallback for characters not in Terminus' glyph set such
as Japanese hiragana.

I now use Terminus Bold 12 instead, which seems to work with the aforementioned
characters fine -- and this night I decided to give the latest DDX revision a
try to see if the drm/radeon changes in Linux 2.6.37 could make a difference
regarding this current bug. It turns out that X will use less than 10% CPU
while idle [*], just like with Terminus Bold 11 with the DDX revision previous
to commit f8fb9312d791af1f77020e8c2d35bb30841ed9aa "RADEONPrepareAccess_CS:
fallback to DFS when pixmap is in VRAM". Performance drops again if I switch
back to Terminus Bold 11, CPU usage sky-rocketing above 50%.

I can't perceive much difference between both font sizes other than line
spacing. Perhaps this has something to do with this bug -- overlapping glyph
regions maybe?

I'm not sure if this contributes anything to the possibility of fixing this
bug, but I thought I'd mention just in case.

[*] "idle" here stands for a maximized Konsole window on a 1280x800 display
with 'top' running on foreground in the active tab.

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