Hi, On Mon, 1 Aug 2011, Michael Jones wrote: > 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. Consider getnstimeofday(). It's not OMAP-specific; there are several examples in the Linux codebase[1]; and if you use a higher-resolution clocksource, the resolution should also increase (try disabling CONFIG_OMAP_32K_TIMER). 1. http://git.kernel.org/?p=linux%2Fkernel%2Fgit%2Ftorvalds%2Flinux-2.6.git&a=search&h=HEAD&st=grep&s=getnstimeofday - Paul -- 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
