kernel/sched.c

/* */
This source file includes following definitions.
sys_ni_syscall
math_state_restore
math_emulate
schedule
sys_pause
wake_up
wake_up_interruptible
__sleep_on
interruptible_sleep_on
sleep_on
add_timer
del_timer
count_active_tasks
calc_load
second_overflow
timer_bh
do_timer
sys_alarm
sys_getpid
sys_getppid
sys_getuid
sys_geteuid
sys_getgid
sys_getegid
sys_nice
show_task
show_state
sched_init
   1 /*
   2  *  linux/kernel/sched.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  */
   6 
   7 /*
   8  * 'sched.c' is the main kernel file. It contains scheduling primitives
   9  * (sleep_on, wakeup, schedule etc) as well as a number of simple system
  10  * call functions (type getpid(), which just extracts a field from
  11  * current-task
  12  */
  13 
  14 #include <linux/config.h>
  15 #include <linux/signal.h>
  16 #include <linux/sched.h>
  17 #include <linux/timer.h>
  18 #include <linux/kernel.h>
  19 #include <linux/kernel_stat.h>
  20 #include <linux/sys.h>
  21 #include <linux/fdreg.h>
  22 #include <linux/errno.h>
  23 #include <linux/time.h>
  24 #include <linux/ptrace.h>
  25 #include <linux/segment.h>
  26 #include <linux/delay.h>
  27 #include <linux/interrupt.h>
  28 
  29 #include <asm/system.h>
  30 #include <asm/io.h>
  31 #include <asm/segment.h>
  32 
  33 #define TIMER_IRQ 0
  34 
  35 #include <linux/timex.h>
  36 
  37 /*
  38  * kernel variables
  39  */
  40 long tick = 1000000 / HZ;               /* timer interrupt period */
  41 volatile struct timeval xtime;          /* The current time */
  42 int tickadj = 500/HZ;                   /* microsecs */
  43 
  44 /*
  45  * phase-lock loop variables
  46  */
  47 int time_status = TIME_BAD;     /* clock synchronization status */
  48 long time_offset = 0;           /* time adjustment (us) */
  49 long time_constant = 0;         /* pll time constant */
  50 long time_tolerance = MAXFREQ;  /* frequency tolerance (ppm) */
  51 long time_precision = 1;        /* clock precision (us) */
  52 long time_maxerror = 0x70000000;/* maximum error */
  53 long time_esterror = 0x70000000;/* estimated error */
  54 long time_phase = 0;            /* phase offset (scaled us) */
  55 long time_freq = 0;             /* frequency offset (scaled ppm) */
  56 long time_adj = 0;              /* tick adjust (scaled 1 / HZ) */
  57 long time_reftime = 0;          /* time at last adjustment (s) */
  58 
  59 long time_adjust = 0;
  60 long time_adjust_step = 0;
  61 
  62 int need_resched = 0;
  63 
  64 /*
  65  * Tell us the machine setup..
  66  */
  67 int hard_math = 0;              /* set by boot/head.S */
  68 int x86 = 0;                    /* set by boot/head.S to 3 or 4 */
  69 int ignore_irq13 = 0;           /* set if exception 16 works */
  70 int wp_works_ok = 0;            /* set if paging hardware honours WP */ 
  71 
  72 /*
  73  * Bus types ..
  74  */
  75 int EISA_bus = 0;
  76 
  77 extern int _setitimer(int, struct itimerval *, struct itimerval *);
  78 unsigned long * prof_buffer = NULL;
  79 unsigned long prof_len = 0;
  80 
  81 #define _S(nr) (1<<((nr)-1))
  82 
  83 extern void mem_use(void);
  84 
  85 extern int timer_interrupt(void);
  86 asmlinkage int system_call(void);
  87 
  88 static unsigned long init_kernel_stack[1024];
  89 struct task_struct init_task = INIT_TASK;
  90 
  91 unsigned long volatile jiffies=0;
  92 
  93 struct task_struct *current = &init_task;
  94 struct task_struct *last_task_used_math = NULL;
  95 
  96 struct task_struct * task[NR_TASKS] = {&init_task, };
  97 
  98 long user_stack [ PAGE_SIZE>>2 ] ;
  99 
 100 struct {
 101         long * a;
 102         short b;
 103         } stack_start = { & user_stack [PAGE_SIZE>>2] , KERNEL_DS };
 104 
 105 struct kernel_stat kstat =
 106         { 0, 0, 0, { 0, 0, 0, 0 }, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
 107 
 108 /*
 109  * int 0x80 entry points.. Moved away from the header file, as
 110  * iBCS2 may also want to use the '<linux/sys.h>' headers..
 111  */
 112 #ifdef __cplusplus
 113 extern "C" {
 114 #endif
 115 
 116 int sys_ni_syscall(void)
     /*  */
 117 {
 118         return -EINVAL;
 119 }
 120 
 121 fn_ptr sys_call_table[] = { sys_setup, sys_exit, sys_fork, sys_read,
 122 sys_write, sys_open, sys_close, sys_waitpid, sys_creat, sys_link,
 123 sys_unlink, sys_execve, sys_chdir, sys_time, sys_mknod, sys_chmod,
 124 sys_chown, sys_break, sys_stat, sys_lseek, sys_getpid, sys_mount,
 125 sys_umount, sys_setuid, sys_getuid, sys_stime, sys_ptrace, sys_alarm,
 126 sys_fstat, sys_pause, sys_utime, sys_stty, sys_gtty, sys_access,
 127 sys_nice, sys_ftime, sys_sync, sys_kill, sys_rename, sys_mkdir,
 128 sys_rmdir, sys_dup, sys_pipe, sys_times, sys_prof, sys_brk, sys_setgid,
 129 sys_getgid, sys_signal, sys_geteuid, sys_getegid, sys_acct, sys_phys,
 130 sys_lock, sys_ioctl, sys_fcntl, sys_mpx, sys_setpgid, sys_ulimit,
 131 sys_olduname, sys_umask, sys_chroot, sys_ustat, sys_dup2, sys_getppid,
 132 sys_getpgrp, sys_setsid, sys_sigaction, sys_sgetmask, sys_ssetmask,
 133 sys_setreuid,sys_setregid, sys_sigsuspend, sys_sigpending,
 134 sys_sethostname, sys_setrlimit, sys_getrlimit, sys_getrusage,
 135 sys_gettimeofday, sys_settimeofday, sys_getgroups, sys_setgroups,
 136 sys_select, sys_symlink, sys_lstat, sys_readlink, sys_uselib,
 137 sys_swapon, sys_reboot, sys_readdir, sys_mmap, sys_munmap, sys_truncate,
 138 sys_ftruncate, sys_fchmod, sys_fchown, sys_getpriority, sys_setpriority,
 139 sys_profil, sys_statfs, sys_fstatfs, sys_ioperm, sys_socketcall,
 140 sys_syslog, sys_setitimer, sys_getitimer, sys_newstat, sys_newlstat,
 141 sys_newfstat, sys_uname, sys_iopl, sys_vhangup, sys_idle, sys_vm86,
 142 sys_wait4, sys_swapoff, sys_sysinfo, sys_ipc, sys_fsync, sys_sigreturn,
 143 sys_clone, sys_setdomainname, sys_newuname, sys_modify_ldt,
 144 sys_adjtimex, sys_mprotect, sys_sigprocmask, sys_create_module,
 145 sys_init_module, sys_delete_module, sys_get_kernel_syms, sys_quotactl,
 146 sys_getpgid, sys_fchdir, sys_bdflush };
 147 
 148 /* So we don't have to do any more manual updating.... */
 149 int NR_syscalls = sizeof(sys_call_table)/sizeof(fn_ptr);
 150 
 151 #ifdef __cplusplus
 152 }
 153 #endif
 154 
 155 /*
 156  *  'math_state_restore()' saves the current math information in the
 157  * old math state array, and gets the new ones from the current task
 158  *
 159  * Careful.. There are problems with IBM-designed IRQ13 behaviour.
 160  * Don't touch unless you *really* know how it works.
 161  */
 162 asmlinkage void math_state_restore(void)
     /*  */
 163 {
 164         __asm__ __volatile__("clts");
 165         if (last_task_used_math == current)
 166                 return;
 167         timer_table[COPRO_TIMER].expires = jiffies+50;
 168         timer_active |= 1<<COPRO_TIMER; 
 169         if (last_task_used_math)
 170                 __asm__("fnsave %0":"=m" (last_task_used_math->tss.i387));
 171         else
 172                 __asm__("fnclex");
 173         last_task_used_math = current;
 174         if (current->used_math) {
 175                 __asm__("frstor %0": :"m" (current->tss.i387));
 176         } else {
 177                 __asm__("fninit");
 178                 current->used_math=1;
 179         }
 180         timer_active &= ~(1<<COPRO_TIMER);
 181 }
 182 
 183 #ifndef CONFIG_MATH_EMULATION
 184 
 185 asmlinkage void math_emulate(long arg)
     /*  */
 186 {
 187   printk("math-emulation not enabled and no coprocessor found.\n");
 188   printk("killing %s.\n",current->comm);
 189   send_sig(SIGFPE,current,1);
 190   schedule();
 191 }
 192 
 193 #endif /* CONFIG_MATH_EMULATION */
 194 
 195 static unsigned long itimer_ticks = 0;
 196 static unsigned long itimer_next = ~0;
 197 static unsigned long lost_ticks = 0;
 198 
 199 /*
 200  *  'schedule()' is the scheduler function. It's a very simple and nice
 201  * scheduler: it's not perfect, but certainly works for most things.
 202  * The one thing you might take a look at is the signal-handler code here.
 203  *
 204  *   NOTE!!  Task 0 is the 'idle' task, which gets called when no other
 205  * tasks can run. It can not be killed, and it cannot sleep. The 'state'
 206  * information in task[0] is never used.
 207  *
 208  * The "confuse_gcc" goto is used only to get better assembly code..
 209  * Djikstra probably hates me.
 210  */
 211 asmlinkage void schedule(void)
     /*  */
 212 {
 213         int c;
 214         struct task_struct * p;
 215         struct task_struct * next;
 216         unsigned long ticks;
 217 
 218 /* check alarm, wake up any interruptible tasks that have got a signal */
 219 
 220         cli();
 221         ticks = itimer_ticks;
 222         itimer_ticks = 0;
 223         itimer_next = ~0;
 224         sti();
 225         need_resched = 0;
 226         p = &init_task;
 227         for (;;) {
 228                 if ((p = p->next_task) == &init_task)
 229                         goto confuse_gcc1;
 230                 if (ticks && p->it_real_value) {
 231                         if (p->it_real_value <= ticks) {
 232                                 send_sig(SIGALRM, p, 1);
 233                                 if (!p->it_real_incr) {
 234                                         p->it_real_value = 0;
 235                                         goto end_itimer;
 236                                 }
 237                                 do {
 238                                         p->it_real_value += p->it_real_incr;
 239                                 } while (p->it_real_value <= ticks);
 240                         }
 241                         p->it_real_value -= ticks;
 242                         if (p->it_real_value < itimer_next)
 243                                 itimer_next = p->it_real_value;
 244                 }
 245 end_itimer:
 246                 if (p->state != TASK_INTERRUPTIBLE)
 247                         continue;
 248                 if (p->signal & ~p->blocked) {
 249                         p->state = TASK_RUNNING;
 250                         continue;
 251                 }
 252                 if (p->timeout && p->timeout <= jiffies) {
 253                         p->timeout = 0;
 254                         p->state = TASK_RUNNING;
 255                 }
 256         }
 257 confuse_gcc1:
 258 
 259 /* this is the scheduler proper: */
 260 #if 0
 261         /* give processes that go to sleep a bit higher priority.. */
 262         /* This depends on the values for TASK_XXX */
 263         /* This gives smoother scheduling for some things, but */
 264         /* can be very unfair under some circumstances, so.. */
 265         if (TASK_UNINTERRUPTIBLE >= (unsigned) current->state &&
 266             current->counter < current->priority*2) {
 267                 ++current->counter;
 268         }
 269 #endif
 270         c = -1;
 271         next = p = &init_task;
 272         for (;;) {
 273                 if ((p = p->next_task) == &init_task)
 274                         goto confuse_gcc2;
 275                 if (p->state == TASK_RUNNING && p->counter > c)
 276                         c = p->counter, next = p;
 277         }
 278 confuse_gcc2:
 279         if (!c) {
 280                 for_each_task(p)
 281                         p->counter = (p->counter >> 1) + p->priority;
 282         }
 283         if(current != next)
 284                 kstat.context_swtch++;
 285         switch_to(next);
 286         /* Now maybe reload the debug registers */
 287         if(current->debugreg[7]){
 288                 loaddebug(0);
 289                 loaddebug(1);
 290                 loaddebug(2);
 291                 loaddebug(3);
 292                 loaddebug(6);
 293         };
 294 }
 295 
 296 asmlinkage int sys_pause(void)
     /*  */
 297 {
 298         current->state = TASK_INTERRUPTIBLE;
 299         schedule();
 300         return -ERESTARTNOHAND;
 301 }
 302 
 303 /*
 304  * wake_up doesn't wake up stopped processes - they have to be awakened
 305  * with signals or similar.
 306  *
 307  * Note that this doesn't need cli-sti pairs: interrupts may not change
 308  * the wait-queue structures directly, but only call wake_up() to wake
 309  * a process. The process itself must remove the queue once it has woken.
 310  */
 311 void wake_up(struct wait_queue **q)
     /*  */
 312 {
 313         struct wait_queue *tmp;
 314         struct task_struct * p;
 315 
 316         if (!q || !(tmp = *q))
 317                 return;
 318         do {
 319                 if ((p = tmp->task) != NULL) {
 320                         if ((p->state == TASK_UNINTERRUPTIBLE) ||
 321                             (p->state == TASK_INTERRUPTIBLE)) {
 322                                 p->state = TASK_RUNNING;
 323                                 if (p->counter > current->counter)
 324                                         need_resched = 1;
 325                         }
 326                 }
 327                 if (!tmp->next) {
 328                         printk("wait_queue is bad (eip = %08lx)\n",((unsigned long *) q)[-1]);
 329                         printk("        q = %p\n",q);
 330                         printk("       *q = %p\n",*q);
 331                         printk("      tmp = %p\n",tmp);
 332                         break;
 333                 }
 334                 tmp = tmp->next;
 335         } while (tmp != *q);
 336 }
 337 
 338 void wake_up_interruptible(struct wait_queue **q)
     /*  */
 339 {
 340         struct wait_queue *tmp;
 341         struct task_struct * p;
 342 
 343         if (!q || !(tmp = *q))
 344                 return;
 345         do {
 346                 if ((p = tmp->task) != NULL) {
 347                         if (p->state == TASK_INTERRUPTIBLE) {
 348                                 p->state = TASK_RUNNING;
 349                                 if (p->counter > current->counter)
 350                                         need_resched = 1;
 351                         }
 352                 }
 353                 if (!tmp->next) {
 354                         printk("wait_queue is bad (eip = %08lx)\n",((unsigned long *) q)[-1]);
 355                         printk("        q = %p\n",q);
 356                         printk("       *q = %p\n",*q);
 357                         printk("      tmp = %p\n",tmp);
 358                         break;
 359                 }
 360                 tmp = tmp->next;
 361         } while (tmp != *q);
 362 }
 363 
 364 static inline void __sleep_on(struct wait_queue **p, int state)
     /*  */
 365 {
 366         unsigned long flags;
 367         struct wait_queue wait = { current, NULL };
 368 
 369         if (!p)
 370                 return;
 371         if (current == task[0])
 372                 panic("task[0] trying to sleep");
 373         current->state = state;
 374         add_wait_queue(p, &wait);
 375         save_flags(flags);
 376         sti();
 377         schedule();
 378         remove_wait_queue(p, &wait);
 379         restore_flags(flags);
 380 }
 381 
 382 void interruptible_sleep_on(struct wait_queue **p)
     /*  */
 383 {
 384         __sleep_on(p,TASK_INTERRUPTIBLE);
 385 }
 386 
 387 void sleep_on(struct wait_queue **p)
     /*  */
 388 {
 389         __sleep_on(p,TASK_UNINTERRUPTIBLE);
 390 }
 391 
 392 static struct timer_list * next_timer = NULL;
 393 
 394 void add_timer(struct timer_list * timer)
     /*  */
 395 {
 396         unsigned long flags;
 397         struct timer_list ** p;
 398 
 399         if (!timer)
 400                 return;
 401         timer->next = NULL;
 402         p = &next_timer;
 403         save_flags(flags);
 404         cli();
 405         while (*p) {
 406                 if ((*p)->expires > timer->expires) {
 407                         (*p)->expires -= timer->expires;
 408                         timer->next = *p;
 409                         break;
 410                 }
 411                 timer->expires -= (*p)->expires;
 412                 p = &(*p)->next;
 413         }
 414         *p = timer;
 415         restore_flags(flags);
 416 }
 417 
 418 int del_timer(struct timer_list * timer)
     /*  */
 419 {
 420         unsigned long flags;
 421         unsigned long expires = 0;
 422         struct timer_list **p;
 423 
 424         p = &next_timer;
 425         save_flags(flags);
 426         cli();
 427         while (*p) {
 428                 if (*p == timer) {
 429                         if ((*p = timer->next) != NULL)
 430                                 (*p)->expires += timer->expires;
 431                         timer->expires += expires;
 432                         restore_flags(flags);
 433                         return 1;
 434                 }
 435                 expires += (*p)->expires;
 436                 p = &(*p)->next;
 437         }
 438         restore_flags(flags);
 439         return 0;
 440 }
 441 
 442 unsigned long timer_active = 0;
 443 struct timer_struct timer_table[32];
 444 
 445 /*
 446  * Hmm.. Changed this, as the GNU make sources (load.c) seems to
 447  * imply that avenrun[] is the standard name for this kind of thing.
 448  * Nothing else seems to be standardized: the fractional size etc
 449  * all seem to differ on different machines.
 450  */
 451 unsigned long avenrun[3] = { 0,0,0 };
 452 
 453 /*
 454  * Nr of active tasks - counted in fixed-point numbers
 455  */
 456 static unsigned long count_active_tasks(void)
     /*  */
 457 {
 458         struct task_struct **p;
 459         unsigned long nr = 0;
 460 
 461         for(p = &LAST_TASK; p > &FIRST_TASK; --p)
 462                 if (*p && ((*p)->state == TASK_RUNNING ||
 463                            (*p)->state == TASK_UNINTERRUPTIBLE ||
 464                            (*p)->state == TASK_SWAPPING))
 465                         nr += FIXED_1;
 466         return nr;
 467 }
 468 
 469 static inline void calc_load(void)
     /*  */
 470 {
 471         unsigned long active_tasks; /* fixed-point */
 472         static int count = LOAD_FREQ;
 473 
 474         if (count-- > 0)
 475                 return;
 476         count = LOAD_FREQ;
 477         active_tasks = count_active_tasks();
 478         CALC_LOAD(avenrun[0], EXP_1, active_tasks);
 479         CALC_LOAD(avenrun[1], EXP_5, active_tasks);
 480         CALC_LOAD(avenrun[2], EXP_15, active_tasks);
 481 }
 482 
 483 /*
 484  * this routine handles the overflow of the microsecond field
 485  *
 486  * The tricky bits of code to handle the accurate clock support
 487  * were provided by Dave Mills (Mills@UDEL.EDU) of NTP fame.
 488  * They were originally developed for SUN and DEC kernels.
 489  * All the kudos should go to Dave for this stuff.
 490  *
 491  * These were ported to Linux by Philip Gladstone.
 492  */
 493 static void second_overflow(void)
     /*  */
 494 {
 495         long ltemp;
 496         /* last time the cmos clock got updated */
 497         static long last_rtc_update=0;
 498         extern int set_rtc_mmss(unsigned long);
 499 
 500         /* Bump the maxerror field */
 501         time_maxerror = (0x70000000-time_maxerror < time_tolerance) ?
 502           0x70000000 : (time_maxerror + time_tolerance);
 503 
 504         /* Run the PLL */
 505         if (time_offset < 0) {
 506                 ltemp = (-(time_offset+1) >> (SHIFT_KG + time_constant)) + 1;
 507                 time_adj = ltemp << (SHIFT_SCALE - SHIFT_HZ - SHIFT_UPDATE);
 508                 time_offset += (time_adj * HZ) >> (SHIFT_SCALE - SHIFT_UPDATE);
 509                 time_adj = - time_adj;
 510         } else if (time_offset > 0) {
 511                 ltemp = ((time_offset-1) >> (SHIFT_KG + time_constant)) + 1;
 512                 time_adj = ltemp << (SHIFT_SCALE - SHIFT_HZ - SHIFT_UPDATE);
 513                 time_offset -= (time_adj * HZ) >> (SHIFT_SCALE - SHIFT_UPDATE);
 514         } else {
 515                 time_adj = 0;
 516         }
 517 
 518         time_adj += (time_freq >> (SHIFT_KF + SHIFT_HZ - SHIFT_SCALE))
 519             + FINETUNE;
 520 
 521         /* Handle the leap second stuff */
 522         switch (time_status) {
 523                 case TIME_INS:
 524                 /* ugly divide should be replaced */
 525                 if (xtime.tv_sec % 86400 == 0) {
 526                         xtime.tv_sec--; /* !! */
 527                         time_status = TIME_OOP;
 528                         printk("Clock: inserting leap second 23:59:60 GMT\n");
 529                 }
 530                 break;
 531 
 532                 case TIME_DEL:
 533                 /* ugly divide should be replaced */
 534                 if (xtime.tv_sec % 86400 == 86399) {
 535                         xtime.tv_sec++;
 536                         time_status = TIME_OK;
 537                         printk("Clock: deleting leap second 23:59:59 GMT\n");
 538                 }
 539                 break;
 540 
 541                 case TIME_OOP:
 542                 time_status = TIME_OK;
 543                 break;
 544         }
 545         if (xtime.tv_sec > last_rtc_update + 660)
 546           if (set_rtc_mmss(xtime.tv_sec) == 0)
 547             last_rtc_update = xtime.tv_sec;
 548 }
 549 
 550 /*
 551  * disregard lost ticks for now.. We don't care enough.
 552  */
 553 static void timer_bh(void * unused)
     /*  */
 554 {
 555         unsigned long mask;
 556         struct timer_struct *tp;
 557 
 558         cli();
 559         while (next_timer && next_timer->expires == 0) {
 560                 void (*fn)(unsigned long) = next_timer->function;
 561                 unsigned long data = next_timer->data;
 562                 next_timer = next_timer->next;
 563                 sti();
 564                 fn(data);
 565                 cli();
 566         }
 567         sti();
 568         
 569         for (mask = 1, tp = timer_table+0 ; mask ; tp++,mask += mask) {
 570                 if (mask > timer_active)
 571                         break;
 572                 if (!(mask & timer_active))
 573                         continue;
 574                 if (tp->expires > jiffies)
 575                         continue;
 576                 timer_active &= ~mask;
 577                 tp->fn();
 578                 sti();
 579         }
 580 }
 581 
 582 /*
 583  * The int argument is really a (struct pt_regs *), in case the
 584  * interrupt wants to know from where it was called. The timer
 585  * irq uses this to decide if it should update the user or system
 586  * times.
 587  */
 588 static void do_timer(struct pt_regs * regs)
     /*  */
 589 {
 590         unsigned long mask;
 591         struct timer_struct *tp;
 592 
 593         long ltemp;
 594 
 595         /* Advance the phase, once it gets to one microsecond, then
 596          * advance the tick more.
 597          */
 598         time_phase += time_adj;
 599         if (time_phase < -FINEUSEC) {
 600                 ltemp = -time_phase >> SHIFT_SCALE;
 601                 time_phase += ltemp << SHIFT_SCALE;
 602                 xtime.tv_usec += tick + time_adjust_step - ltemp;
 603         }
 604         else if (time_phase > FINEUSEC) {
 605                 ltemp = time_phase >> SHIFT_SCALE;
 606                 time_phase -= ltemp << SHIFT_SCALE;
 607                 xtime.tv_usec += tick + time_adjust_step + ltemp;
 608         } else
 609                 xtime.tv_usec += tick + time_adjust_step;
 610 
 611         if (time_adjust)
 612         {
 613             /* We are doing an adjtime thing. 
 614              *
 615              * Modify the value of the tick for next time.
 616              * Note that a positive delta means we want the clock
 617              * to run fast. This means that the tick should be bigger
 618              *
 619              * Limit the amount of the step for *next* tick to be
 620              * in the range -tickadj .. +tickadj
 621              */
 622              if (time_adjust > tickadj)
 623                time_adjust_step = tickadj;
 624              else if (time_adjust < -tickadj)
 625                time_adjust_step = -tickadj;
 626              else
 627                time_adjust_step = time_adjust;
 628              
 629             /* Reduce by this step the amount of time left  */
 630             time_adjust -= time_adjust_step;
 631         }
 632         else
 633             time_adjust_step = 0;
 634 
 635         if (xtime.tv_usec >= 1000000) {
 636             xtime.tv_usec -= 1000000;
 637             xtime.tv_sec++;
 638             second_overflow();
 639         }
 640 
 641         jiffies++;
 642         calc_load();
 643         if ((VM_MASK & regs->eflags) || (3 & regs->cs)) {
 644                 current->utime++;
 645                 if (current != task[0]) {
 646                         if (current->priority < 15)
 647                                 kstat.cpu_nice++;
 648                         else
 649                                 kstat.cpu_user++;
 650                 }
 651                 /* Update ITIMER_VIRT for current task if not in a system call */
 652                 if (current->it_virt_value && !(--current->it_virt_value)) {
 653                         current->it_virt_value = current->it_virt_incr;
 654                         send_sig(SIGVTALRM,current,1);
 655                 }
 656         } else {
 657                 current->stime++;
 658                 if(current != task[0])
 659                         kstat.cpu_system++;
 660 #ifdef CONFIG_PROFILE
 661                 if (prof_buffer && current != task[0]) {
 662                         unsigned long eip = regs->eip;
 663                         eip >>= 2;
 664                         if (eip < prof_len)
 665                                 prof_buffer[eip]++;
 666                 }
 667 #endif
 668         }
 669         if (current == task[0] || (--current->counter)<=0) {
 670                 current->counter=0;
 671                 need_resched = 1;
 672         }
 673         /* Update ITIMER_PROF for the current task */
 674         if (current->it_prof_value && !(--current->it_prof_value)) {
 675                 current->it_prof_value = current->it_prof_incr;
 676                 send_sig(SIGPROF,current,1);
 677         }
 678         for (mask = 1, tp = timer_table+0 ; mask ; tp++,mask += mask) {
 679                 if (mask > timer_active)
 680                         break;
 681                 if (!(mask & timer_active))
 682                         continue;
 683                 if (tp->expires > jiffies)
 684                         continue;
 685                 mark_bh(TIMER_BH);
 686         }
 687         cli();
 688         itimer_ticks++;
 689         if (itimer_ticks > itimer_next)
 690                 need_resched = 1;
 691         if (next_timer) {
 692                 if (next_timer->expires) {
 693                         next_timer->expires--;
 694                         if (!next_timer->expires)
 695                                 mark_bh(TIMER_BH);
 696                 } else {
 697                         lost_ticks++;
 698                         mark_bh(TIMER_BH);
 699                 }
 700         }
 701         sti();
 702 }
 703 
 704 asmlinkage int sys_alarm(long seconds)
     /*  */
 705 {
 706         struct itimerval it_new, it_old;
 707 
 708         it_new.it_interval.tv_sec = it_new.it_interval.tv_usec = 0;
 709         it_new.it_value.tv_sec = seconds;
 710         it_new.it_value.tv_usec = 0;
 711         _setitimer(ITIMER_REAL, &it_new, &it_old);
 712         return(it_old.it_value.tv_sec + (it_old.it_value.tv_usec / 1000000));
 713 }
 714 
 715 asmlinkage int sys_getpid(void)
     /*  */
 716 {
 717         return current->pid;
 718 }
 719 
 720 asmlinkage int sys_getppid(void)
     /*  */
 721 {
 722         return current->p_opptr->pid;
 723 }
 724 
 725 asmlinkage int sys_getuid(void)
     /*  */
 726 {
 727         return current->uid;
 728 }
 729 
 730 asmlinkage int sys_geteuid(void)
     /*  */
 731 {
 732         return current->euid;
 733 }
 734 
 735 asmlinkage int sys_getgid(void)
     /*  */
 736 {
 737         return current->gid;
 738 }
 739 
 740 asmlinkage int sys_getegid(void)
     /*  */
 741 {
 742         return current->egid;
 743 }
 744 
 745 asmlinkage int sys_nice(long increment)
     /*  */
 746 {
 747         int newprio;
 748 
 749         if (increment < 0 && !suser())
 750                 return -EPERM;
 751         newprio = current->priority - increment;
 752         if (newprio < 1)
 753                 newprio = 1;
 754         if (newprio > 35)
 755                 newprio = 35;
 756         current->priority = newprio;
 757         return 0;
 758 }
 759 
 760 static void show_task(int nr,struct task_struct * p)
     /*  */
 761 {
 762         static char * stat_nam[] = { "R", "S", "D", "Z", "T", "W" };
 763 
 764         printk("%-8s %3d ", p->comm, (p == current) ? -nr : nr);
 765         if (((unsigned) p->state) < sizeof(stat_nam)/sizeof(char *))
 766                 printk(stat_nam[p->state]);
 767         else
 768                 printk(" ");
 769         if (p == current)
 770                 printk(" current  ");
 771         else
 772                 printk(" %08lX ", ((unsigned long *)p->tss.esp)[3]);
 773         printk("%5lu %5d %6d ",
 774                 p->tss.esp - p->kernel_stack_page, p->pid, p->p_pptr->pid);
 775         if (p->p_cptr)
 776                 printk("%5d ", p->p_cptr->pid);
 777         else
 778                 printk("      ");
 779         if (p->p_ysptr)
 780                 printk("%7d", p->p_ysptr->pid);
 781         else
 782                 printk("       ");
 783         if (p->p_osptr)
 784                 printk(" %5d\n", p->p_osptr->pid);
 785         else
 786                 printk("\n");
 787 }
 788 
 789 void show_state(void)
     /*  */
 790 {
 791         int i;
 792 
 793         printk("                         free                        sibling\n");
 794         printk("  task             PC    stack   pid father child younger older\n");
 795         for (i=0 ; i<NR_TASKS ; i++)
 796                 if (task[i])
 797                         show_task(i,task[i]);
 798 }
 799 
 800 void sched_init(void)
     /*  */
 801 {
 802         int i;
 803         struct desc_struct * p;
 804 
 805         bh_base[TIMER_BH].routine = timer_bh;
 806         if (sizeof(struct sigaction) != 16)
 807                 panic("Struct sigaction MUST be 16 bytes");
 808         set_tss_desc(gdt+FIRST_TSS_ENTRY,&init_task.tss);
 809         set_ldt_desc(gdt+FIRST_LDT_ENTRY,&default_ldt,1);
 810         set_system_gate(0x80,&system_call);
 811         p = gdt+2+FIRST_TSS_ENTRY;
 812         for(i=1 ; i<NR_TASKS ; i++) {
 813                 task[i] = NULL;
 814                 p->a=p->b=0;
 815                 p++;
 816                 p->a=p->b=0;
 817                 p++;
 818         }
 819 /* Clear NT, so that we won't have troubles with that later on */
 820         __asm__("pushfl ; andl $0xffffbfff,(%esp) ; popfl");
 821         load_TR(0);
 822         load_ldt(0);
 823         outb_p(0x34,0x43);              /* binary, mode 2, LSB/MSB, ch 0 */
 824         outb_p(LATCH & 0xff , 0x40);    /* LSB */
 825         outb(LATCH >> 8 , 0x40);        /* MSB */
 826         if (request_irq(TIMER_IRQ,(void (*)(int)) do_timer)!=0)
 827                 panic("Could not allocate timer IRQ!");
 828 }
/* */
root/kernel/sched.c

DEFINITIONS
