sg_get_cpu_stats

Section: C Library Functions (3)
Updated: $Date: 2005/04/25 11:25:45 $
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NAME

sg_get_cpu_stats, sg_get_cpu_stats_diff, sg_get_cpu_percents - get cpu usage

SYNOPSIS

#include <statgrab.h>

sg_cpu_percents *sg_get_cpu_percents(void);

sg_cpu_stats *sg_get_cpu_stats(void);

sg_cpu_stats *sg_get_cpu_stats_diff(void);

DESCRIPTION

sg_get_cpu_stats() and sg_get_cpu_stats_diff() both return static pointers of type sg_cpu_stats. sg_get_cpu_stats() returns the total amount of "ticks" the operating system has spent in each of the different states. sg_get_cpu_stats_diff() returns the difference in "ticks" for each of the states since last time sg_get_cpu_stats_diff() or sg_get_cpu_stats() was called. If it has never been called, it will return the result of sg_get_cpu_stats().

The value stored (the "ticks") will vary between operating systems. For example Solaris has a total of 100 per second, while Linux has substantially more. Also, different operating systems store different information - you won't find nice cpu on Solaris for example.

Because of this, you will ideally always want to work on a scale against the total, or in percentages.

sg_get_cpu_percents() returns a pointer to a static sg_cpu_percents. The function calls sg_get_cpu_stats_diff() and changes the values into percentages. If it has never been called before (and nor has sg_get_cpu_stats() or sg_get_cpu_stats_diff()), the returned percentages will be the systems total ever since its uptime. (Unless the counters have cycled)

RETURN VALUES

There are two structures returned by the CPU statistics functions.


typedef struct{
        long long user;
        long long kernel;
        long long idle;
        long long iowait;
        long long swap;
        long long nice;
        long long total;
        time_t systime;
}sg_cpu_stats;


typedef struct{
        float user;
        float kernel;
        float idle;
        float iowait;
        float swap;
        float nice;
        time_t time_taken;
}sg_cpu_percents;

user kernel idle iowait swap nice: The different CPU states.
systime time_taken: The time taken in seconds since the last call of the function, or the system time.

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