"),    ,     
.    ,   "".

,  schedule_tick ()     
      need_resched  -
.  SMP-       
  .      4.

    update_process_times ()  
update_times (),     .

void update_times(void)
(

unsigned long ticks;

ticks = jiffies - wall_jiffies;

if (ticks) {

wall jiffies += ticks;

update_wall_time(ticks) ;

}
last time_offset = 0;

calc_load(ticks) ;

}

  ticks     
       .  -
   , ,  1.    
   ,     ,   
.   ,      -
 .          
 .   wall_ jiffies   -
 ticks,      jiffies   
   .    update_
wall time ()  ,     xtime,  -
   .    calc_load ()
 ,      ,  
 update_times ()  .

 do_timer ()    -  -
,      , 
 xtime_lock      .

    1/HZ , .. 1000      
PC.

 

    (time of day, wall time,  ) -
   kernel/timer .  .

struct timespec xtime;

    221