Linux C Get CPU Utilization (2)

In the last blog post, we talked about how to get the results of executing the command line in Linux, and eventually get CPU usage, but unfortunately it is:

1) via Top-n 1 | The CPU usage obtained by the GREP CPU is not refreshed, and the results of the first execution are only available for each read.

2) may cause a conflict on signal

The new code solves the principle:

Calculate CPU usage by reading data from/proc/stat

#include <stdio.h><stdlib.h><sys/stat.h><sys/types.h>  <string.h><fcntl.h><unistd.h><errno.h>  <sys/statfs.h><sys/vfs.h>

#define FILEBUFFER_LENGTH 5000
#define EMPTY_STR ""

#define Cpu_part "/proc/stat"

struct Cpu_cost//storing CPU data structure body
{
long int user;
long int nice;
long int system;
long int idle;
long int iowait;
a long int IRQ;
long int softirq;
};

Opens the file specified by filename, from which to read the linenumber line
Return value: Successfully returned 1, failed to return 0
int Get_file_line (char *result,char *filename,int linenumber)
{
FILE *filepointer;
int i=0;
Char Buffer[filebuffer_length];
Char *temp;

memset (buffer, ' n ', filebuffer_length*sizeof (char));
strcpy (BUFFER,EMPTY_STR);

if ((filename==null) | | | (Result==null))
{
return 0;
}

if (! ( Filepointer=fopen (FileName, "RB")))
{return 0;}

while ((!feof (Filepointer)) && (I<linenumber))
{
if (!fgets (Buffer,filebuffer_length,filepointer))
{
return 0;
}
i++;//almost forgot to add this sentence again.
}

/* printf ("\n%d\n", sizeof (*result));
if (strlen (buffer) >sizeof (*result))//Can not write this, although Fgets read a line will be added to the end of ' ", but sizeof (result) results are the size of the type of result itself, So I can't count that. When a static array is passed into a function, it is only known inside the function that it is a pointer
{
return 0;
}*/

if (0!=fclose (Filepointer))
{
return 0;
}

if (0!=strcmp (BUFFER,EMPTY_STR))
{
while (null!= (temp=strstr (buffer, "\ n")))
{
*temp= ' + ';
}

while (null!= (temp=strstr (buffer, "\ r")))
{
*temp= ' + ';
}

strcpy (Result,buffer);
}else
{
strcpy (RESULT,EMPTY_STR);
return 0;
}

return 1;
}

CPU-related data is read from/proc/stat and stored in the structure
int GetCpuInfo2 (Pcpu_cost cpuInfo)
{
Char cpustr[500];
if (null==cpuinfo)
{
printf ("\ngetcpuinfo param null!\n");
return 0;
}

if (1==get_file_line (cpustr,cpu_part,1))
{

SSCANF (Cpustr, "%*s%ld%ld-%ld%ld%ld%ld",& (cpuinfo->user),& (cpuinfo->nice),& (cpuinfo-> System),& (Cpuinfo->idle),& (cpuinfo->iowait),& (CPUINFO->IRQ),& (CPUINFO->SOFTIRQ)); /modified more than one%ld, resulting in an error
return 1;
}

return 0;
}

Calculates CPU usage based on two read CPU data, resulting in a result of between 0~1000 and 1000 representing a utilization rate of 100%
Parameter two: The first read CPU data structure body
Parameter three: The second read CPU data structure body
int CalCpuInfo2 (int *cpuusage,pcpu_cost cpu1,pcpu_cost CPU2)
{
long int total=0,total1=0,total2=0,idle=0,idle1=0,idle2=0,result=0;
if ((null==cpuusage) && (NULL==CPU1) && (NULL==CPU2))
{
printf ("\ncalcpuinfo2 param null!\n");
return 0;

}

Total1=cpu1->user+cpu1->nice+cpu1->system+cpu1->idle+cpu1->iowait+cpu1->irq+cpu1->softirq ;//Total CPU time read for the first time
Total2=cpu2->user+cpu2->nice+cpu2->system+cpu2->idle+cpu2->iowait+cpu2->irq+cpu2->softirq ;//The total CPU time of the second read

if (TOTAL2>TOTAL1)
{
total=total2-total1;//Total time Difference

idle1=cpu1->idle;//idle time for first read
idle2=cpu2->idle;//idle time for second read
idle=idle2-idle1;//Idle time Difference

result=100000* (Total-idle);//Busy time difference
result=result/total;//utilization = busy time/Total time
*cpuusage= (int) result;
return 1;
}
return 0;

}

Interval 0.6s reads CPU data and calculates CPU usage, and returns the percentage of CPU usage
Float Getcpuusage ()
{
Cpu_cost cpu1,cpu2;
int usage_i=0;

float usage_f=0;

if (1==getcpuinfo2 (&CPU1))
{
Usleep (600000);
if (1==getcpuinfo2 (&CPU2))
{
if (1==calcpuinfo2 (&USAGE_I,&CPU1,&CPU2))
{
usage_f= (float) usage_i/1000;
printf ("%d%0.3f\n", usage_i,usage_f);
return usage_f;
}
}
}

return-1;

}

Of course, because it is copied and pasted from a file, the above code may have problems on the header file, and the code is not necessarily accurate comments, to be screened by users themselves.

Linux C Get CPU Utilization (2)