Hmm, is this one of the articles you looked at? http://www.virtualdub.org/blog/pivot/entry.php?id=106
That is definitely a bit off-putting. Not sure about the power save mode issue, but I think someone told me that tbb::tick_count gets the value from the same CPU each time. http://www.threadingbuildingblocks.org/documentation.php >From the TBB reference manual: 7 Timing Parallel programming is about speeding up wall clock time, which is the real time that it takes a program to run. Unfortunately, some of the obvious wall clock timing routines provided by operating systems do not always work reliably across threads, because the hardware thread clocks are not synchronized. The library provides support for timing across threads. The routines are wrappers around operating services that we have verified as safe to use across threads. >From the TBB tutorial: 8 Timing ... Unlike some timing interfaces, tick_count is guaranteed to be safe to use across threads. It is valid to subtract tick_count values that were created by different threads. A tick_count difference can be converted to seconds. The resolution of tick_count corresponds to the highest resolution timing service on the platform that is valid across threads in the same process. Since the CPU timer registers are not valid across threads on some platforms, this means that the resolution of tick_count can not be guaranteed to be consistent across platforms. I'd be interested to see whether this works for you. Chad On 5/28/09 8:31 AM, "Rush Manbert" <[email protected]> wrote: > Hi Chad, > > It uses QueryPerformanceCounter on Windows. I'm going to go back and > test my QPF code again. It's possible (oh so remotely possible ;-) > that I screwed something up. > > Best regards, > Rush > > On May 27, 2009, at 4:06 PM, Chad Walters wrote: > <snip> >> >> 2. Did you look at Intel's Threading Building Blocks tick_count >> implementation? >> >
