[Intel-gfx] QtQuick/Qt5 application produces high CPU load with Intel i915

[Benjamin Federau]

Hello,

I'm running a QtQuick application using shaders on an older Intel(R) Atom(TM) CPU N270   @ 1.60GHz with Intel Corporation Mobile 945GM/GMS/GME, 943/940GML Express Integrated Graphics Controller.

My setup is 
  * Ubuntu 16.04 (32-bit)
  * Qt 5.9.2
  * Mesa: 17.4.0
  * Intel i8xx, i9xx display driver: 2.99.917
  * XServer: 1.18.4

The test application is the QtQuick samegame example. When I start the app with the INTEL_DEBUG=perf env variable i get the following messages
....
ENTER FALLBACK 10000: Program 
LEAVE FALLBACK Program 
i915_program_error: Exceeded max nr indirect texture lookups (6 out of 4)
...

and the CPU load goes up to 100% and the app reacts very slow. Btw. is there another debugging/tracing configuration which i can use to narrow down the problem a bit more?
With the perf or oprofile tool I see that the most CPU time is consumed by i915_dri.so.

Are there any known regressions regarding QtQuick/Qt 5/Shaders and the i915 driver on Ubuntu 16.04.

Regards
-
Benjamin Federau

-- 
  
M.Sc. Benjamin Federau 
Integration Engineer 
  
basysKom GmbH 
Robert-Bosch-Str. 7 | 64293 Darmstadt | Germany 
benjamin.federau at basyskom.com  | www.basyskom.com 
  
Handelsregister: Darmstadt HRB 9352 
Geschaeftsfuehrung: Dr.-Ing. Eva Brucherseifer, Heike Ziegler
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