Hi Paul, On 08/02/2011 03:41 AM, Paul Walmsley wrote: > > 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 Thanks, I took your suggestion and it served my purpose just fine. -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
