cpu 사용량

TOP 명령어에서 보이는 내용은 /proc/stat를 파싱한 결과라고 한다.

 

• user: normal processes executing in user mode
• nice: niced processes executing in user mode
• system: processes executing in kernel mode
• idle: twiddling thumbs
• iowait: waiting for I/O to complete
• irq: servicing interrupts
• softirq: servicing softirqs

            from : http://www.linuxhowtos.org/System/procstat.htm

#include <string.h>

#include <stdio.h>

#include <stdlib.h>

void  get_cpu_info( char *cpu_info, int *total, int *idle )

{

        int num = 0;

        char *token, *bp;

        char buffer[1024];

        FILE *fp;

        if(( fp = fopen( "/proc/stat", "r" )) != NULL )

        {

                *total = 0;

                *idle  = 0;

                fgets( buffer, 1024, fp );

                for( token = strtok_r( buffer, " ", &bp ), num = 0; token != NULL; token = strtok_r( NULL, " ", &bp ), num++ )

                {

                        switch( num )

                        {

                                case 0 : break;

                                case 4 : *idle     = atoi(token);

                                default : (*total) += atoi(token); break;

                        }

                }

        }

}

int  calculate_cpu( int curr_idle, int curr_total , int prev_idle, int prev_total  )

{

        int diff_total;

        int diff_idle;

        int cpu;

        diff_idle  = curr_idle  - prev_idle;

        diff_total = curr_total - prev_total;

        cpu = (1000*(diff_total - diff_idle ) / diff_total+5)/10;

        return cpu;

}

int main()

{

        int curr_idle  = 0, prev_idle  = 0;

        int curr_total = 0, prev_total = 0;

        int  curr_percentage;

        char cpu_info[1024];

        while( 1 ){

                get_cpu_info( cpu_info, &curr_total, &curr_idle );

                curr_percentage = calculate_cpu( curr_idle, curr_total, prev_idle, prev_total );

                fprintf( stderr,"CPU = %d%%\n", curr_percentage );

                prev_total = curr_total;

                prev_idle  = curr_idle;

                sleep(1);

        }

}