very bad, and very weird, scrolling text performance xorg 1.5.3 intel 2.5.1 GM965

Jeffrey Baker jwbaker at
Mon Dec 15 09:37:22 PST 2008

On Mon, Dec 15, 2008 at 2:26 AM, Michel Dänzer
<michel at> wrote:
> On Mon, 2008-12-15 at 10:57 +0100, Lukas Hejtmanek wrote:
>> On Sun, Dec 14, 2008 at 06:48:52PM -0500, Thomas Jaeger wrote:
>> > You really need the glyph cache in the X server to get decent text
>> > performance out of the 2.5 intel driver.  The patches are pretty
>> > straightforward to backport, but it is my understanding that a 1.6
>> > server will be uploaded to jaunty soon, so you might want to wait for that.
>> I wonder whether the Intel driver can get at least close to Nvidia driver.
>> I ran x11perf on Nvidia system and Xserver *without* the glyph cache. Compared
>> to these numbers, the Intel driver seems to be a bit comic with 56k glyphs/sec
>> with EXA or 215k glyphs/sec with UXA.
> Note that the glyph cache is specific to EXA, which the nvidia driver
> doesn't use. UXA on the other hand may have the glyph cache in its copy
> of the EXA code.
> I'm not sure what's the bottleneck for the intel driver at this point,
> the radeon driver easily gets 500k/s and beyond (which is still a far
> cry from the numbers you measured, but already seems to mostly avoid it
> being any practical limitation). Some of it may just be down to the
> hardware (memory bandwidth, shader units etc.).

I seriously doubt it, since performance was far better last week, last
month, and a year ago with the same hardware.  I think we can safely
pin this current problem on the software.

Even if it were limited at 50kglyphs/s, the 7m character output would
still come out in 140s, not 400s.


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