dpmd_cpu.c

Linux下动态电源管理(Dynamic Power Management)的用户守护进程

#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define KVER_26 0
#define KVER_24 1

struct cpu_interval {
	int min;
	int max;
	int nice_scale;
};

static unsigned int c_user, c_nice, c_sys, c_time;
static unsigned int c_user_old, c_nice_old, c_sys_old, c_time_old;
static unsigned int delta_time;
static unsigned int kernel_version = KVER_24;

int cpu_parse(const char *ev, void **obj)
{
	struct cpu_interval *ret;

	ret = malloc(sizeof(struct cpu_interval));
	if (ret == NULL) {
		printf("Unable to make room for a cpu interval (%s)\n", 
		       strerror(errno));
		return -1;
	}
	ret->min = ret->max = 0;
	ret->nice_scale = 3;
#if 0
	printf("cpu interval: %s\n", ev);
#endif

	sscanf(ev, "%d-%d,%d", &(ret->min), &(ret->max), &(ret->nice_scale));

#if 0
	printf("read MIN:%d MAX:%d SCALE:%d\n", 
	       ret->min, ret->max, ret->nice_scale);
#endif

	if (ret->nice_scale == 0) {
		printf("nice_scale value out of range(%d), resetting to default value(3).\n",
		       ret->nice_scale);
		ret->nice_scale = 3;
	}

	if (ret->min > ret->max) {
		printf("Min higher than Max?\n");
		free(ret);
		return -1;
	}

	*obj = ret;
	return 0;
}

int cpu_evaluate(const void *s) {
	int cpu_percent = 0;
	unsigned int weighted_activity_old = 0;
	unsigned long int delta_activity = 0, weighted_activity = 0;

	const struct cpu_interval *c = (const struct cpu_interval *) s;

	weighted_activity = c_user + c_nice / c->nice_scale + c_sys;
	weighted_activity_old = c_user_old + c_nice_old / c->nice_scale + c_sys_old;
	delta_activity = weighted_activity - weighted_activity_old;
#if 0
	printf("CPU delta_activity=%ld delta_time=%d weighted_activity=%ld.\n",
	       delta_activity, delta_time, weighted_activity);
#endif

	if ( delta_activity > delta_time || delta_time <= 0) {
		cpu_percent = 100;
	} else {
		cpu_percent = delta_activity * 100 / delta_time;
	}
#if 0
	printf("CPU usage = %d.\n", cpu_percent);
	printf("called with min=%d max=%d\n", c->min, c->max);
#endif

	return (cpu_percent >= c->min && cpu_percent <= c->max) ? 1 : 0;
}

int get_cpu(void) {
	FILE* fp;
	int f;
	unsigned long int c_idle=0, c_iowait=0, c_irq=0, c_softirq=0; /* for linux 2.6 only */

	c_user_old = c_user;
	c_nice_old = c_nice;
	c_sys_old = c_sys;
	c_time_old = c_time;

	/* read raw jiffies... */
	fp = fopen ("/proc/stat", "r");
	if (!fp) {
		printf("/proc/stat: %s\n", strerror(errno));
		return -1;
	}

	do {
		f = fscanf (fp,
				"cpu  %u %u %u %lu %lu %lu %lu",
				&c_user, &c_nice, &c_sys, &c_idle, &c_iowait, &c_irq, &c_softirq);

	} while ((f!=4 && kernel_version==KVER_24) || (f!=7 && kernel_version==KVER_26));
	fclose(fp);
#if 0
	printf("CPU c_user=%d c_nice=%d c_sys=%d c_idle=%ld "
	       "c_iowait=%ld c_irq=%ld c_softirq=%ld.\n",
	       c_user, c_nice, c_sys, c_idle, c_iowait, c_irq, c_softirq);
#endif

	/* calculate total jiffies */
	c_sys += c_irq + c_softirq;
	c_idle += c_iowait;
	c_time = c_user + c_nice + c_sys + c_idle;
	/* calculate delta time */
	delta_time = c_time - c_time_old;

	/*
	   weighted_activity = c_user + c_nice / 3 + c_sys;
	   delta_activity = weighted_activity - old_weighted_activity;
	   old_weighted_activity = weighted_activity;
	*/

	return 0;
}