static ushort thread_group_cpu_share(struct task_struct *task)
{
struct task_cputime times;
cputime_t num_load, div_load, total_time;
ushort share;
my_thread_group_cputime(task, ×);
total_time = cputime_add(times.utime, times.stime);
/*
last_cputime == 0 means that the timer_function has been called
for the first time and we have to collect info before doing any
check.
*/
if (unlikely(last_cputime == 0)) {
share = 0;
printk(KERN_INFO "sendsig: timer initialization completed\n");
} else {
/*
Let's compute the share of cpu usage for the last WAIT_TIMEOUT
seconds
*/
num_load = cputime_sub(total_time, last_cputime) * 100;
div_load = jiffies_to_cputime(wait_timeout * HZ);
share = (ushort)cputime_div(num_load, div_load);
printk(KERN_DEBUG "sendsig: computed cpu share for process %d: %d\n",
pid, share);
}
/*
Update last_cputime
*/
last_cputime = total_time;
return share;
}
/*
* Divide and limit the result to res >= 1
*
* This is necessary to prevent signal delivery starvation, when the result of
* the division would be rounded down to 0.
*/
static inline cputime_t cputime_div_non_zero(cputime_t time, unsigned long div)
{
cputime_t res = cputime_div(time, div);
return max_t(cputime_t, res, 1);
}
