Hi All,I know this is not email list for programming questions but it relatesto Kernel as well, in fact relying on kernel. Could someone pleasethrough a light or guide me to the right direction.Problem Statement: High CPU clock speed/freqRequirement: Obtain a stable CPU clock ticks/speed/freq onSuse 11.1 with kernel 2.6.27.7-9Questions: Please refer to the bottom of this pageArtifacts in Use:-----------------------------------OS: Suse 11.1GCC Version: 4.3.2 (Suse Linux) [gcc_4_3-brach revision141291]Kernel: 2.6.27.7-9Kernel Mods: * Un-check the Tickless option * Timer Frequency - 1000Hz * Preempt kernelOthers 1-----------OS: Suse 10.2GCC Version: 4.1.2 20061115 (prerelease)(SUSE Linux)Kernel: 2.6.18.2-34-defaultKernel Mods: * Preemptible Kernel(Low-Latency Desktop) (NEW) * Preempt The Big Kernel Lock(NEW) * Timer frequency (NEW) - 1000Hz (NEW)Others 2-----------OS: Suse 9.3GCC Version: 3.3.5 20050117 (prerelease)(SUSE Linux)Kernel 2.6.11.4-20a-defaultKernel Mods: NoneI executed the following c++ code on the above stated buildsCODE - file name test.cpp#include <signal.h>#include <sys/time.h>#include <iostream>#include <cstdlib>using namespace std;long long int counter = 0;struct timeval last_time;struct timeval curr_time;double dif = 0.0;double freq_sum = 0.0;double reps = 0.0;double freq_min = 99999.0;double freq_max = 0.0;long long int num_too_low = 0;void time_check(int data){ // work out the frequecy of the SIGALRMs ++counter; if (counter >= 1000) { // need to work out time since last 1000 ticks gettimeofday(&curr_time, NULL); dif = ((curr_time.tv_usec + curr_time.tv_sec * 1000000) - (last_time.tv_usec + last_time.tv_sec * 1000000)); double freq = (counter / dif) * 1000000; freq_sum = ((freq_sum * reps) + freq) / (reps + 1) ; ++reps; cout << "Frequency = " << freq << " reps= " << dif / 1000000 <<endl; if (freq_min > freq) freq_min = freq; if (freq_max < freq) freq_max = freq; if (freq < 950) ++num_too_low; last_time = curr_time; counter = 0; }}int main (int argc, char * argv[]){ cout << "go" /* << "\a \a \a" */ << endl; int res; gettimeofday(&last_time, NULL); struct sigaction action; struct itimerval timer_value; timer_value.it_value.tv_sec = 0; timer_value.it_value.tv_usec = 1; timer_value.it_interval.tv_sec = 0; timer_value.it_interval.tv_usec = 1; action.sa_handler = time_check; action.sa_flags = SA_NOMASK; sigemptyset(&action.sa_mask); sigaction( SIGALRM, &action, NULL); res = setitimer( ITIMER_REAL, &timer_value, NULL ); if (res == -1) cout << "error in setitimer" << endl; cout << "Starting CPU Test program" << endl; // loop for a long time while (reps < 3000.0) { sleep(1); } cout << "average CPU frequency = " << freq_sum << endl; cout << "reps = " << reps << endl; cout << "Min = " << freq_min << " Max = " << freq_max << endl; cout << "number of low = " << num_too_low << endl; return 0;}Compiled the above code with "g++ -o test test.cpp"Run the above code with "./test"Observations:SUSE Version AVG. Frequency AVG. REPSSuse 9.3 999.xxx to 990.xxx reps > 1(on average)Suse 10.2 999.xxx to 998.xxx reps (1- 1.001)Suse 10.3 1000.xxx to 912.xxx reps (1 - 1.090)Suse 11.1 0 to 324263.xxx reps(-2e-0.6 upto 0.005112)Suse 11.1 - Options:- Turn off ACPI in options when booting with clock=tsc | clock=pitObservations for suse 11.1 with options acpi=off and clock=tsc |clock=pitSUSE Version AVG. Frequency AVG. REPSSuse 11.1 710.xxx to 999.xxx reps(1.37xx to 1.0002)Hardware used for Suse 11.1 - HP Pavilion Slimline s3821uk Desktop PC(NQ808AA) specifications - HP Home & Home Office products testing no other application/s were running.Question:* Is my c++ code correct?* Am I using the correct way to get the clock ticks or is there morereliable tchnique avaliable to do this?* Is that a problem with new Kernel if so is it a known issue ?* Do I need to modify the Kernel to obtain regular and stable clock tickat 1000 Hz ?* Do I have to upgrade the Kernel ?* Would be great, if pointed to the right direction for solution (e.g.another forum) if no solution at hand.ThanksSubhan********************************************************************This email and any attachments are confidential to the intendedrecipient and may also be privileged. If you are not the intendedrecipient please delete it from your system and notify the sender.You should not copy it or use it for any purpose nor disclose ordistribute its contents to any other person.********************************************************************