I have a function in a driver which takes ~50ms to execute, which I've measured by reading jiffies at the beginning and end. But jiffies only counts at 128Hz on my system, so this was a very coarse measurement. Now I would like to find out more exactly where the time is going inside this function. So my basic question is, what is the best way to measure lapsed time with reasonable resolution on an OMAP? As I had done with the jiffies measurement, what I imagined was inserting lines into my function, sampling the value of some counter at various points within it. This approach is crude but simple and would suffice for my case. Since it must be a very common task, I thought I'd ask here what the recommended approach is. I see a few directions... 1. Using the OMAP's 32kHz timer, which is provided as a "struct clocksource". It seems like what I would want is to call clocksource_32k.read(), but I don't know how to retrieve clocksource_32k. 2. Using the ARM core's Performance Monitor Count Registers. This seems to be what perf_event uses. I'm not familiar with perf_events, but it sounds like I would also need to build 'perf', which according to http://www.omappedia.org/wiki/Using_perf isn't possible to cross-compile. I don't want to tackle that without some reassurance that it is the right/only way. I am currently using a 2.6.38 kernel. thanks, Michael MATRIX VISION GmbH, Talstrasse 16, DE-71570 Oppenweiler Registergericht: Amtsgericht Stuttgart, HRB 271090 Geschaeftsfuehrer: Gerhard Thullner, Werner Armingeon, Uwe Furtner, Erhard Meier -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
