Hi, > Current revisions of Cortex-A8 core have a hardware bug in performance > monitoring unit, which makes it very unreliable in Oprofile. > > We discussed this problem offlist with Richard Woodruff some time ago and he > suggested to use GPTIMER to get better event samples collection frequency, > comparable to the one typically used with the hardware performance counters. > The use of GPTIMER instead of a standard oprofile timer based backend makes > the process of profiling applications less painful and more precise.
Cool. This will help a lot. I did get some more information from ARM on core bug which is now in their official errata. As a future enhancement it should be possible to use PMNC event counters as long as they do not overflow. This might allow a GPT - PMNC hybrid. The 32bit counters can run for a good amount before rolling. Additionally, the bug is greatly minimized in future stepping of CortexA8. It will be a while before that core goes into a production device. Thanks, Richard W. -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
