新手学堂 Linux操作系统中关于负载的定义

//kernel/timer.c

1254 active_tasks = count_active_tasks();

1256 CALC_LOAD(avenrun[0], EXP_1, active_tasks);
1257 CALC_LOAD(avenrun[1], EXP_5, active_tasks);
1258 CALC_LOAD(avenrun[2], EXP_15, active_tasks);

//include/linux/sched.h

 110 #define FSHIFT      11      /* nr of bits of precision */
 111 #define FIXED_1     (1< 112 #define LOAD_FREQ   (5*HZ)      /* 5 sec intervals */
 113 #define EXP_1       1884        /* 1/exp(5sec/1min) as fixed-point */
 114 #define EXP_5       2014        /* 1/exp(5sec/5min) */
 115 #define EXP_15      2037        /* 1/exp(5sec/15min) */

 117 #define CALC_LOAD(load,exp,n) \
 118     load *= exp; \
 119     load += n*(FIXED_1-exp); \
 120     load >>= FSHIFT;



1946 unsigned long nr_active(void)
1947 {
1948 unsigned long i, running = 0, uninterruptible = 0;
1949
1950 for_each_online_cpu(i) {
1951 running += cpu_rq(i)->nr_running;
1952 uninterruptible += cpu_rq(i)->nr_uninterruptible;
1953 }
1954
1955 if (unlikely((long)uninterruptible < 0))
1956 uninterruptible = 0;
1957
1958 return running + uninterruptible;
1959 }


1226 static unsigned long count_active_tasks(void)
1227 {
1228 return nr_active() * FIXED_1;
1229 }