On 09/27/2010 07:34 AM, Wade Hampton wrote: > Did you look at using the RDTSC instruction to read the > cycle counter? > > http://en.wikipedia.org/wiki/Time_Stamp_Counter > > Sample this over an interval to get an estimate > of the clock frequency based on this counter. > > __inline__ unsigned long long int rdtsc() > { > unsigned long long int x; > __asm__ volatile (".byte 0x0f, 0x31" : "=A" (x)); > return(x); > } > > I use gettimeofday() calls to check the wall-clock time, > usleep(n) to sleep for a long time (second or more), > and rdtsc to compute the cycles.... Seems to work > well. > > Cheers, > -- > Wade Hampton Thank you very much Wade. I confirm that using rdtsc, the delta in tsc values, divided by 60 (using nanosleep) is 798283074.9833333333 ticks per second, which is almost iddentical to what is reported by cpuinfo: cpu MHz : 798.244 No matter what the load factor on the machine, even when the load reached 5 or 6, it is the same value. Well, that's what you get for buying a laptop from a crappy manufacturer that has put in it a fixed unprogrammable clock (oscillator), and put in a lame BIOS that provides no hooks for setting C2 C3 ...etc. I will certainly steer friends and family away from this manufacturer. -- users mailing list users@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe or change subscription options: https://admin.fedoraproject.org/mailman/listinfo/users Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines
