Attachment 577384 Details for Bug 812148 – Added output of CPU usage

Added output of CPU usage

test_select.cpp (text/plain), 4.14 KB, created by Dave Johansen on 2012-04-13 16:53:23 UTC

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Creator: Dave Johansen

Created: 2012-04-13 16:53:23 UTC

Size: 4.14 KB

patch

obsolete

>#include <stdio.h>
>#include <string.h>
>#include <unistd.h>
>#include <sys/select.h>
>#include <sys/types.h>
>#include <iostream>
>
>
>// CPU usage measure taken from https://github.com/fho/code_snippets/blob/master/c/getusage.c
>
>struct pstat{
>    long unsigned int utime_ticks;
>    long int cutime_ticks;
>    long unsigned int stime_ticks;
>    long int cstime_ticks;
>    long unsigned int vsize; // virtual memory size in bytes
>    long unsigned int rss; //Resident Set Size in bytes
>
>    long unsigned int cpu_total_time;
>};
>
>/*
>* read /proc data into the passed struct pstat
>* returns 0 on success, -1 on error
>*/
>int get_usage(const pid_t pid, struct pstat* result){
>    //convert pid to string
>    char pid_s[20];
>    snprintf(pid_s, sizeof(pid_s), "%d", pid);
>    char stat_filepath[30] = "/proc/"; strncat(stat_filepath, pid_s,
>            sizeof(stat_filepath) - strlen(stat_filepath) -1);
>    strncat(stat_filepath, "/stat", sizeof(stat_filepath) -
>            strlen(stat_filepath) -1);
>
>    //Open /proc/stat and /proc/$pid/stat fds successive(dont want that cpu
>    //ticks increases too much during measurements)
>    //open /proc dir, to lock all files and read the results from the
>    FILE *fproc = fopen("/proc", "r");
>    if (fproc == NULL){
>        perror("FOPEN ERROR ");
>        return -1;
>    }
>    //same timefragem
>    FILE *fpstat = fopen(stat_filepath, "r");
>    if(fpstat == NULL){
>        perror("FOPEN ERROR ");
>        return -1;
>    }
>
>    FILE *fstat = fopen("/proc/stat", "r");
>    if(fstat == NULL){
>        perror("FOPEN ERROR ");
>        fclose(fstat);
>        return -1;
>    }
>
>    //read values from /proc/pid/stat
>    bzero(result, sizeof(struct pstat));
>    long int rss;
>    if(fscanf(fpstat, "%*d %*s %*c %*d %*d %*d %*d %*d %*u %*u %*u %*u %*u %lu"
>                "%lu %ld %ld %*d %*d %*d %*d %*u %lu %ld",
>                &result->utime_ticks, &result->stime_ticks,
>                &result->cutime_ticks, &result->cstime_ticks, &result->vsize,
>                &rss) == EOF) {
>        fclose(fpstat);
>        return -1;
>    }
>    fclose(fpstat);
>    result->rss = rss * getpagesize();
>
>    //read+calc cpu total time from /proc/stat
>    long unsigned int cpu_time[10];
>    bzero(cpu_time, sizeof(cpu_time));
>    if(fscanf(fstat, "%*s %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu",
>                &cpu_time[0], &cpu_time[1], &cpu_time[2], &cpu_time[3],
>                &cpu_time[4], &cpu_time[5], &cpu_time[6], &cpu_time[7],
>                &cpu_time[8], &cpu_time[9]) == EOF) {
>        fclose(fstat);
>        return -1;
>    }
>
>    fclose(fstat);
>
>    fclose(fproc);
>
>    for(int i=0; i < 10;i++){
>        result->cpu_total_time += cpu_time[i];
>    }
>
>    return 0;
>}
>
>/*
>* calculates the actual CPU usage(cur_usage - last_usage) in percent
>* cur_usage, last_usage: both last measured get_usage() results
>* ucpu_usage, scpu_usage: result parameters: user and sys cpu usage in %
>*/
>void calc_cpu_usage(const struct pstat* cur_usage, const struct pstat*
>                    last_usage, double* ucpu_usage, double* scpu_usage){
>    const long unsigned int total_time_diff = cur_usage->cpu_total_time -
>                                              last_usage->cpu_total_time;
>
>    *ucpu_usage = 100 * (((cur_usage->utime_ticks + cur_usage->cutime_ticks)
>                    - (last_usage->utime_ticks + last_usage->cutime_ticks))
>                    / (double) total_time_diff);
>
>    *scpu_usage = 100 * ((((cur_usage->stime_ticks + cur_usage->cstime_ticks)
>                    - (last_usage->stime_ticks + last_usage->cstime_ticks))) /
>                    (double) total_time_diff);
>}
>
>
>int main()
>{
>	timeval ts;
>
>	// Get the id of the current process
>	pid_t id = getpid();
>  // The stats structure of the cpu usage
>  pstat currStat, prevStat;
>  double userCpu, systemCpu;
>
>  // Get the CPU stats before starting
>  get_usage(id, &prevStat);
>
>	for (unsigned int ii=0; ii<1000000; ++ii) {
>		ts.tv_sec = 0;
>		ts.tv_usec = 1000;
>		select(0, NULL, NULL, NULL, &ts);
>
>    if ((ii % 1000) == 999) {
>      if (get_usage(id, &currStat) == 0) {
>        calc_cpu_usage(&currStat, &prevStat, &userCpu, &systemCpu);
>        std::cout << "user: " << userCpu << " system: " << systemCpu << '\n';
>			}
>    }
>	}
>
>	return 0;
>}

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