Imagination PowerVR SDK Blog

Memory Management - inexplicable behavior

pvrtrace

#1



Hello,
during the execution of my self-developed application (C++/OpenGL 3D terrain visualization, embedded, current Ubuntu kernel, PowerVR SGX) I observe the following inexplicable behavior: the viewer spins around -> the application hangs frequently (the rotation speed has no effect) - the application hangs on an OpenGL call (glDrawElements() of a triangle strip with texture coordinates) - interesting and for me inexplicable is the output of the used/allocated memory - "top": VIRT (~215m) and RES (~190m) are nearly constant during the execution time (vary by ~ 5m), but the SHR-memory increases during the execution from ~40m to ~120m, the application runs until a SHR-memory of ~120m (run time: ~5 seconds) -> the application hangs (hang time: ~2 seconds), subsequently the SHR-memory is decreased to ~40m and the applications runs again until the next hang (SHR-memory ~40m) and so on. During the described execution time no new data is loaded, all data is already cached.

What is the reason for the app-hang? Why is allocated SHR memory increased/decreased continuously - there is enough free memory available during the entire execution time? What can I do - so that the application is running without the described hangs?

Thanks for your advice and help
Markus


#2

Hi Markus,

What platform are you running on? Can you share your GPU driver version string with us (can be queried with ‘cat /proc/pvr/version’)?

Thanks,
Joe




#3


Hi Joe,
please find below the requested information:
- the application is running on a Gumstix Overo board
- the GPU driver version string: Version CustomerTI_OMAP4430_Linux_GPL sgxddk 17 1.7@867897 (release) /home/Projects/OveroBoard/Kernel/RobertCNelson-stable-kernel-31e5e0c/Graphics_SDK_4_06_00_02/GFX_Linux_KM
System Version String: SGX revision = 1.2.5
 
Thanks for your help,
Markus

#4

Hi Markus,

Thanks for the information.

Can you use PVRTrace to record your application (with data recording enabled) and send us the recorded file, please?

Thanks,
Joe