sg_get_cpu_stats(3)

NAME

sg_get_cpu_stats, sg_get_cpu_stats_r, sg_get_cpu_stats_diff, sg_get_cpu_stats_diff_between, sg_get_cpu_percents, sg_get_cpu_percents_of, sg_get_cpu_percents_r, sg_free_cpu_stats - get cpu usage

SYNOPSIS

#include <statgrab.h>

sg_cpu_percents *sg_get_cpu_percents
(size_t *entries);

sg_cpu_percents *sg_get_cpu_percents_of
(sg_cpu_percent_source cps, size_t *entries);

sg_cpu_percents *sg_get_cpu_percents_r
(const sg_cpu_stats *whereof, size_t *entries);

void sg_free_cpu_percents
(sg_cpu_percents *data);

sg_cpu_stats *sg_get_cpu_stats
(size_t *entries);

sg_cpu_stats *sg_get_cpu_stats_diff
(size_t *entries);

sg_cpu_stats *sg_get_cpu_stats_r
(size_t *entries);

sg_cpu_stats *sg_get_cpu_stats_diff_between
(const sg_cpu_stats *cpu_now, const sg_cpu_stats *cpu_last, size_t *entries);

sg_error sg_free_cpu_stats
(sg_cpu_stats *data);

DESCRIPTION

These are the categories of data delivered by the cpu stats module: sg_get_cpu_stats() and sg_get_cpu_stats_r() deliver native cpu counters since the machine has been started, sg_get_cpu_stats_diff() and sg_get_cpu_stats_diff_between() deliver native cpu counters between two sg_get_cpu_stats() calls and sg_get_cpu_percents_of() and sg_get_cpu_percents_r() deliver correlated relative cpu counters (where total is 100%).

API Shortcut

function	returns	data owner
sg_get_cpu_stats	sg_cpu_stats *	libstatgrab (thread local)
sg_get_cpu_stats_r	sg_cpu_stats *	caller
sg_get_cpu_stats_diff	sg_cpu_stats *	libstatgrab (thread local)
sg_get_cpu_stats_diff_between	sg_cpu_stats *	caller
sg_get_cpu_percents_of	sg_cpu_percents *	libstatgrab (thread local)
sg_get_cpu_percents_r	sg_cpu_percents *	caller

The sg_cpu_stats buffer received from sg_get_cpu_stats_r() and the sg_get_cpu_stats_diff_between() as well as the sg_cpu_percents buffer received from sg_get_cpu_percents_r() must be freed using sg_free_cpu_stats() or the sg_free_cpu_percents(), respectively, when not needed any more. The caller is responsible for doing it.

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.

Modern systems shall provide information about the clock tick resolution by invoking sysconf(_SC_CLK_TCK).

RETURN VALUES

There are two structures returned by the CPU statistics functions.

typedef struct {
        unsigned long long user;
        unsigned long long kernel;
        unsigned long long idle;
        unsigned long long iowait;
        unsigned long long swap;
        unsigned long long nice;
        unsigned long long total;
        unsigned long long context_switches;
        unsigned long long voluntary_context_switches;
        unsigned long long involuntary_context_switches;
        unsigned long long syscalls;
        unsigned long long interrupts;
        unsigned long long soft_interrupts;
        time_t systime;
} sg_cpu_stats;

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