On Sun, Nov 30, 2008 at 2:51 PM, Michael Blizek <[EMAIL PROTECTED]> wrote: > Hi! > > On 13:43 Sun 30 Nov , Mulyadi Santosa wrote: >> Hi All > > ... > >> 2. I suggest to use TSC (TimeStamp Clock) if you use x86 (32 and 64 >> bit). I don't say gettimeofday() won't meet your need, but I think >> reading TSC register is the fastest code path you can get to measure >> timing. > > This sounds great. See http://en.wikipedia.org/wiki/Time_Stamp_Counter > > This seems to have some implications: > - The timestamp counter is not synchronized on all CPUs/cores ==> set the CPU > affinity before starting the Benchmark. > - The time unit is CPU clock cycles or something else (processor dependant), > not microseconds. Frequency scaling and maybe APM_CPU_IDLE are probably not > such a great idea...
yes, you're correct, I forgot about frequency scaling that certainly affects TSC. NB: This is why I like this kind of discussion, it makes everybody smarter... regards, Mulyadi. -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to [EMAIL PROTECTED] Please read the FAQ at http://kernelnewbies.org/FAQ
