loadavg.c

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#include <linux/fs.h>
#include <linux/init.h>
#include <linux/pid_namespace.h>
#include <linux/proc_fs.h>
#include <linux/sched.h>
#include <linux/seq_file.h>
#include <linux/seqlock.h>
#include <linux/time.h>

#define LOAD_INT(x) ((x) >> FSHIFT)
#define LOAD_FRAC(x) LOAD_INT(((x) & (FIXED_1-1)) * 100)

static int loadavg_proc_show(struct seq_file *m, void *v)
{
    unsigned long avnrun[3];

    get_avenrun(avnrun, FIXED_1/200, 0);

    seq_printf(m, "%lu.%02lu %lu.%02lu %lu.%02lu %ld/%d %d\n",
        LOAD_INT(avnrun[0]), LOAD_FRAC(avnrun[0]),
        LOAD_INT(avnrun[1]), LOAD_FRAC(avnrun[1]),
        LOAD_INT(avnrun[2]), LOAD_FRAC(avnrun[2]),
        nr_running(), nr_threads,
        task_active_pid_ns(current)->last_pid);
    return 0;
}

static int loadavg_proc_open(struct inode *inode, struct file *file)
{
    return single_open(file, loadavg_proc_show, NULL);
}

static const struct file_operations loadavg_proc_fops = {
    .open       = loadavg_proc_open,
    .read       = seq_read,
    .llseek     = seq_lseek,
    .release    = single_release,
};

static int __init proc_loadavg_init(void)
{
    proc_create("loadavg", 0, NULL, &loadavg_proc_fops);
    return 0;
}
module_init(proc_loadavg_init);