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www.williamspublishing.com

NOVELL PRESS

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Linux Kernel

DevelopmentSecond Edition

Robert Love

Novell Press, 800 East 96th Street, Indianapolis,

Novell

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32.973.26018.2.75

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32.973.26018.2

. , , Novell Press.

Aufhorued translation from the English language edition published by Novell Press, Copyright 20by Pearson Education, Inc.

All rights reserved. No part of this book shall be reproduced, stored in a retrieval system, or transmted by any means, electronic, mechanical, photocopying, recording, or otherwise, without written permsion from the publisher.

All terms men tione d in this book that are known to be trademarks or service marks have been appr

rialely capitalized. Novell Press cannot attest to the accuracy of this information. Use of a term in this boshould not be regarded as affecting the validity of any trademark or service mark.Russian language edition is published by Williams Publishing House according to the Agreement w

R&I Enterprises International, Copyright 2006

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. 3.3.

, .

TASK_RUNNING (runnable). , , , ( , runqueue,

4. " "). TASK_INTERRUPTIBLE (

, sleeping),..

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. ,

TASK__RUNNING. (wake up)

.

TASK_UNNTERRUPTIBLE TASK_INTERRUPTIBLE,

, .

, , .

, TASK_UNINTERRUPTIBLE

, TASK_INTERRUPTIBLE6.

TASK_ZOMBIE ,

wait4 ().

,

. wait4 (),

.

TASK_STOPPED . . ,

SIGSTOP, SIGTSTP, SIGTTIN SIGTTOU,

, .

.

set_task state(task, state);

/* 'task' 'state' */

. ,

(memory barrier),

(

SMP). :

task>state = state;

set current s t a te (state) set_task_

tate(current, state).

. (executable)

.

. (. 5,

") ,

.

6 "" ,

ps(1) , D, ,

SIGKILL. , ,

, , .

7/26/2019 . Linux 2006

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, " " . current

1.

, . ,

. .

.

Linux .

init, PID

1. i ni t . ini t , , (initscripts) , .

. , ., , (siblings). . task_struct task_struct , parent,

, children. , (current), :

struct task_struct *task = current>parent;

, , :

struct task_struct *task;

struct list_head *list;

list_for_each (list, scurrent>children) {

task = list_entry(list, struct task_struct, sibling);

/* task ,

*/

}

ini t i ni t t ask . , .

1 , 6, "

". ,

. ,

.

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struct task_struct *task

for (task = current; task ! = $init_task; task = task>parent)

/* task init */

, ,

. , , . ,

.

, ,

:

list_entry(task>tasks.next, struct task_struct, tasks)

.

list_entry (task>tasks.prev, struct task_struct, tasks)

next_task (task)

( ), prev_task (task) ( ).

, for_each_process (task)

. task

:

struct task_struct *task;

for_each_process(task) {

/* PID

*/

printk("%s[%d]\n", task>comm, task>pid);

}

, ,

, .

(

).

Unix

.

(spawn).

, ,

. Unix ,

: fork () exec ()8.

8 exec() exec* () .

execve(), execlp(), execle(),

execv() execvp().

7/26/2019 . Linux 2006

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fork() ,

.

PID (

), PPID ( PID

PID ),

, ( ),

exec () .

fork () exec ()

, .

fork()

.

. Linux fork ()

(copyonwrite)

(copyonwrite, COW)

.

.

,

, ,

. , ,

,

(readonly). ,

. ,

, , , exec () fork (),

. ,

fork (),

.

(

10 ),

, Unix .

f o r k ()

Linux fork ()

clone () .

, , (

) . "

Linux" .

f ork( ) ,v fork( ) c l oned clone ()

. clone ()

do_fork ().

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do_f ork (), kernel/fork.. , , copy_pracess () . , copy_process ().

dup_task_struct (), ,

thread_info task_struct , . .

, .

. .

. TASK_

UNINTERRUPTIBLE, , .

copy_process () copy_f lags (), flags task s truct . PF_SUPERPRIV, , . PF_FORKNOEXEC, , exec (), .

get_pid () , PID .

, clone (), , , , (namespace). . .

( 4," ").

, .

do_fork () . opy_process () , .

9.

9 , ,

, .

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, exec () , , , , .

vfork ()

vfork () , fork (), , . , exec () . . 3BSD, fork ()

. , vfork () . Linu

10,

. vfork () (, , , exec () ?), , vfork () . vfork () fork (), Linux 2.2.

vfork () clone (), .

copy_process () vfork_done task_struct NULL.

do_fvork (), , vfork_done ( ).

, , copy_process () , , vfork_done.

mm_release () (, ), vfork_done NULL, .

do_fork()

.

10 Linux. ,

, 2.6

, .

7/26/2019 . Linux 2006

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, ,

,

. ,

.

L i n u x .

.

.

oncurrent programming),

.

Linux . Linux

. Linux

, . Linux

. ,

.

ask_s t r uct (

, , ).

Linux ,

icrosoft Windows Sun Solaris,

(

, lightweight process). " " Linux

. ,

, ,

. Linux

(

)11

.

, , .

,

.

,

. , . Linux,

, , ,

task_struct . ,

.

, , ,

clone () ,

:

Clone (CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_SIGHAND, 0);

11 ( )

Linux .

.

7/26/2019 . Linux 2006

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,

fork (), , ,

,

. , , ,

. , fork ()

:

clone (SIGCHLD, 0);

vfork () :

clone (CLONE_VFORK | CLONE_VM | SIGCHLD, 0);

, clone () ,

,

. . 3.1

clone () .

3 . 1 . c l o n e ()

CLONE_FILES

CLONE_FS

CLONE_IDLETASK

CLONE_NEWNS

CLONE_PARENT

CLONE_PTRACE

CLONE_SETTID

CLONE_SETTLS

CLONE_SIGHAND

CLONE_SYSVSEM

CLONE_THREAD

CLONE_VFOK

CLONE_ONTRACED

CLONE_3T0P

CLONE_CHILD_CLEARTID

CLONE_CHILD_SETTID

CLONE_PARENT_SETTID

CLONE_VM

PID ( (idle) )

TID ?

(thread local storage, TLS)

SEM_UNDO System V

v f ork (): ,

CLONE_PTRACE

TA SK _S TO PP E D

TID

TID

TID

7/26/2019 . Linux 2006

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.

(kernel thread)

, .

, ( mm NULL).

, .

,

.

Linux ,

, pdflush ksoftirq.

.

,

. :

int kernel_thread(int (*fn) (void * ) , void * arg, unsigned long flags)

clone ()

, flags.

task _ s t r uc t .

, fn,

arg.

CLONE_KERNEL, CLONE_FS, CLONE_FILES CLONE_SIGHAND,

flags.

, , ,

Linux ). ,

,

.

.

, .

, , ,

, , ,

, , "".

,

ex i t () ex i t ()

main ()). . ,

,

7/26/2019 . Linux 2006

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. , , doexec (), .

PF_EXITING flags task struct.

del_timer_sync (),

, .

, (BSD process accounting), acct_process () , .

__exit_mm() mm_struc . ( , ), .

exit_sem (). IPC,

.

__exit_files (), __exit_fs () , exit_namespace () exit_signals () , , , .

, ,

. , exitcod

task struct. exit () , .

ex i t not i f (), (reparent)

, i nit. TASK_ZOMBIE.

schedule () (. 4, " "). TASK_ZOMBIE , , .

do_exit () kernel/exit.. , (

). (, , ), , TASK_ZOMBIE. , , , thread inf task struct.

7/26/2019 . Linux 2006

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, .

do_exit ()

, TASK_ZOMBIE . , . , . , task_struct . wait () (

) wait4 (). , . PID . , , .

, release_task (), .

free_uid () . Linux , . , , .

unhash_process () pidhash .

(ptrace), , (pirate) .

put_task_struct () , thread_inf, a , task_struct.

, , , .

""

,

, , , , , . :

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, i n i t . do_exit ()

notif y_ parent (), forge t_or igi na l pa rent (

(reparent),

.

struct task_struct *, *reaper = father;struct list_head *list;

if (father>exit_signal != 1)

reaper = prev_thread(reaper);

else

reaper = child_reaper;

if (reaper == father)

reaper = child_reaper;

reaper

.

, reaper child_reaper

i ni t . ,

,

, .

list_for_each(list, &father>children) {

= list_entry(list, struct task_struct, sibling);

reparent_thread(p, reaper, child_reaper);

}

list_for_each (list, sfather>ptrace__children) {

p = list_entry(list, struct task:_struct, ptrace_list);

reparent_thread(p, reaper, child_reaper);

}

:

child list ,

ptraced child list. ,

, ( 2.6). ptrace,

,

(debugging).

,

.

, ,

, ,

:

.

,

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I n i t w a it () , , , .

. , , . , , Linux , ( task_struct thread_inf), (o n e () f o rk () ),

( exec ()), , ( ait ()) (

exit ()).

, , , , ( ).

, , , .

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7/26/2019 . Linux 2006

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, .

, .

(scheduler) , , . ,

(, , )

, ,

. (multitasking) , Linux. ,

, ,

.

, , . , , ,

. , , .

(runnable). ,

, , , .

, . , .

. , . , , .

, , (, , ..). , Linux 100 ,

.

7/26/2019 . Linux 2006

68/451

(multitasking) : (cooperative) (preemptive,

) . Linux, Unix , . , ,

, . , , (preemption) . , , , . (timesiice). , . . , , . , Linux

, .

, ,

. , ,

(yielding). : , ; ,

; "" , , . , , , . Mac OS 9 . , Unix .

Linux 2.5, . 0(1)

(0(1) scheduler) 1.

Linux , . , (1), 0(1), , , .

1 (1) " ". , ,

,

. , " ",

, " ".

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(policy)

, , .

. , .

,

,

(I/0bound), , (processorbound).

,

. , ,

, (

, ,

, , ).

, , ,

.

, ,

.

,

, . , , ,

, . ,

. ,

, .

.

: X Windows ,

.

,

. ,

, ,

.

:

( , low latency)

hroughput).

, , ,

, . Unix , ,

, .

, ,

7/26/2019 . Linux 2006

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, . Linux ( ), .. , , . , , ,

.

(prioritybased). ,

. , ,

( , roundrobin), .. . , Linux, . , , , . , .

Linux (dynamic prioritybased), .

, , . , , , , . Linux . ,, , , . .

Linux .

nice, 20 19, 0. nice

(ic . , ). nice ( ) niie ( ). nice , . nice 20 , nice 19 . nice Unix .

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(realtime priority), . 0 99. . Linux POSIX. Unix .

(timeslice

2) , ,

, . , , . , . , . , , . , , , , , , , .

, . , , , 20 . Linux , . Linux , . Linux ( 4.1). , Linux

. , , . .

, . , , 100 , 100 , .

20 .

2 timeslice ( ) quantum () proces

sor slice. Linux timeslice.

7/26/2019 . Linux 2006

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5 100 800

. 4.1.

,

,

, ,

.

, ,

. , ,

, .

, ,

.

. Linux

, .

.

, Linux

. TASK_RUNNING,

. ,

, , ,

( ,

). ,

,

.

:

.

,

( ,

, ). ,

,

. .

,

,

,

100%.

7/26/2019 . Linux 2006

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: ,

. , , .

, ,

.

. ,

,

. ,

.

, ,

.

.

Linux. ,

, ,

Linux.

Linux

kernel/sched.c.

,

2.5. ,

.

, .

(1) . ,

,

,

.

SMP.

.

SMP (SMP affinity). ,

,

, , ,

.

.

.

.

(fairness).

.

,

.

7/26/2019 . Linux 2006

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, 12,

, .

.

(runqueue).

kernel/sched.c 3 s t r u c t ru nqu e u e . .

. . , ,

. ,

. , . .

struct runqueue {

spinlock_t lock; /* */

unsigned long nr_rinning; /* , */

unsigned long nr_switches; /* */

unsigned long expired timestamp; /* */

unsigned long nr_uninterruptible; /* */

unsigned long long timestamp last tick; /*

*/

struct task_struct *curr; /* ,

*/

struct task_struct *idle; /* */

struct mm_struct *prev_mm; /* mm_struct

*/

struct prio_array "active; /* */

struct prio_array 'expired; /* */struct prio_array arrays[2]; /* */

struct task_3truct *migration_thread; /*

*/

struct list_head migration_queue; /*

*/

atomic_t nr_iowait; /* , */

};

3 : kernel/sched., i n c l u d e / l i n u x / s c h e d . h ? , .

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, , . cpu_rq (processor) , , . t his_rq () , . , task_rq(task) ,

. ,

( 8, " "). , (, , ). , , , . , ,

. tapk_rq_lock () ask_rq_unlock(), .

struct runqueue *rq;

unsigned long flags;

rq = task_rq_lock(task, &flags);

/* */

task_rq_unlock (rq,&flags);

this_rq_lock (), , rq__unlock (structrunqueue *rq), .

, , , ( 8, ", ).

, , .

/* , ... */

if(rqllock] ;

spin_lock(Srq2>lock) ;

} else (

spin_lock(Srq2>lock) ;

spin_lock(&rql>lock)

/* ... */

/ , ... */

spin_unlock(brql>lock) ;spin_unlock(&rq2>lock);

}

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double_rq_lock ()double_rq_unlock ()

. .

double_rq_lock(rql, rq2);

/* ...*/

double_rq_unlock(rql, rq2) ;

, , . 8, "

" 9, " ".

:

.

. ,

. , , ,

.

, (

), ,

. (, spinning),

, ,

. , ,

, ,

, . ,

,

.

, .

,

. .

,

, ,

, .

,

. 8 9 .

(priority arrays):

. kernel/sched.c

s t r uc t pr io_array.

, 0(1).

,

. (priority bitmap),

,

.

struct prio_array (

int nr_active; /* */

unsigned long bitmap[BITMAP_SIZE]; /* */

struct list head queue[MAX_PRIO];/* */

};

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MAX_PRIO .

140. ,

s t r uct list_head. BITMAP_SIZE

, unsigned long.

. 140 32

, BITMAP_SIZE 5. , bitmap , 160 .

bitmap,

.

0.

( TASK_RUNNING),

bitmap 1.

, , 7, ,

7.

. , , ,

, . ,

Linux

(find first set) .

sched_find_first_bit ().

4.

.

,

st r uct l ist_head. queue.

.

,

, ,

. ,

,

.

.

nr_active,

.

( Linux)

, .

4 86 bsfl,

cntlzw.

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, , .

for ( ) (

}

. .

. , (n), n .

. .

.

, ( Linux).

Linux . : (active) (expired). , , .

, . , , , . .

, , . schedule ().

struct prio_array array = rq>active;

if (!array>nr_active) {

rq>active = rq>expired;

rq>expired = array;

}

, O(1). , (1) . .

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schedule ()

schedule (). (sleep), a . schedule ()

. , , .

schedule () , , . .

struct task_struct *prev, *next;

struct list_head *queue;

struct prio_array *array;

int idx;

prev = current;

array = rq>active;

idx = sched_find_first_bit(array>bitmap);

queue = array>queue + idx;

next = list__entry(queue>next, struct task struct, run_ist);

. . ,

. , . . 4.2.

schedule()

0 0

sch e d_f i nd_f i r s t_se t ( )

7 7

140 139 139

. 4.2. (1) Linux

, 7

7/26/2019 . Linux 2006

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prev next , (next).

, p re v , , next, context_switch (), .

. . , , , . , . . , schedule () . .

, , , . , , , , . , .

, nice. 20 19, 0. 19 , 20 . nice s t a t i c _ p r i o task_struct . , , . , prio. .

e f f e c t i v e _ p r i o () . ic 5 5,

. , , nice, 10, , 5. , nice, 10,

, , 12. , , , , nice.

, , . , ,

. (sleep). , . ,

7/26/2019 . Linux 2006

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, . , , ; , .

Linux , ,

, , . sleep_avg t a s k _ s t r u c t . MAX_SLEEP_AVG, 10 . , sleep_avg , , sleep_avg MAX_SLEEP_AVG. , (timer tick) , 0.

, , . , , , . , , , : , , . . , , , . , . sleep_avg. , nice, nice.

, , , nice ( ). . ,

. . , , . task_timeslice () . . , . MAX_TIMESLICE,

200 . MIN_TIMESLICE, 10 .

7/26/2019 . Linux 2006

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, ( nice,

),

100 , . 4.1.

4.1.

nice

,

+19 5 (MIN_TIMESUCE)

0 100 (DEF_TIMESLICE)

20 800 (MAX_TIMESLICE)

:

, ,

. ,

:

, .

,

O(1). , ,

, ,

"" .

. ,

,

, .

scheduler_tick (),

( 10, " "),

.

struct task_struct *task = current;

struct runqueue *rq = this_rq();

if (!task>time_slice) {

if (!TASK_INTERACTIVE(task) || EXPIRED_STARVING(rq))enqueue_task(task, rq>expired);

else

enqueue_task(task, rq>active);

}

,

. ,

.

SK_INTERACTIVE ().

nice , "". nice( ),

. nice, 19,

7/26/2019 . Linux 2006

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. , nice, 20,

, .

nice, , .. ,

, ,

. , EXPIRED_STARVING (),

, ,

(startving), .

,

, ,

. ,

.

, .

( , , sleeping, blocked) ,

. ,

, ""

, , ,

, .

,

.

,

. ,

( 9,

" ").

,

read () , .

.

:

, (wail queue),

sc heduled

. (wake up) : ,

.

,

: TASK_INTERRUPTIBLE TASK_UNINTERRUPTIBLE.

, TASK_UNINTERRUPTIBLE

, TASK_INTERRUPTIBLE

.

, ,

, .

(wait queue). ,

7/26/2019 . Linux 2006

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.

wait_queue_head_t.

DECLARE_WAIT_QUEUE_HEAD ()

ini t_waitqueue_head ().

. , , ,

, . ,

(race).

,

.

:

, .

.

.

/* q ( ),

*/

DECLARE_WAITQUEUE(wait, current) ;

add_wait_queue(q, &wait);

set_current_State(TASK_INTERRUPTIBLE); /* TASK_UNINTERRUPTIBLE */

/* condition ,

*/

while (!condition)

schedule() ;set_current_state(TASK_RUNNING);

remove_wait queue(q, &wait);

, ,

.

DECLARE_WAITQUEUE ().

add wait_queue () .

, , , . ,

, wake_up () ,

.

TASK_INTERRUPTIBLE TASK_

UNINTERRUPTIBLE.

, . ,

.

, schedule ().

,

. ,

7/26/2019 . Linux 2006

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. , schedule () .

, TASK_RUNNING remove_wait_queue().

, , . , . , schedule () ; , ERESTARTSYS; .

(wake up) wake_up (), , , . try_to_wake_up () , TASK_RUNNING, activate_task () need_resched , , , . , , wakeup () , . , , VFS wake_up () , , .

, . , , , , : , , , , (. 4.3).

, Linux

. , . , , . ? , , , , ? , ,

. .

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add_wait_q ueje() , TASK_INTER RUPTIB LE s chedu le (). sc he du le d deact ivate_task(), .

,

TASK_R UNNING

, , , try_to_wake_up() TASK_RUNNING, activate_task() schedule() . remove_wait_quaue () .

. 4,3. (sleeping) (wake up)

, , . , ,

,

. k e r n e l / s c h e d .

load_balance (). . schedule (), . 1 , , 200 . lo a d _b a la n c e () ,

, .

, , . , l o a d b a l a n c e ( ) s c h e d u l e ( ) ,

, . , . , , . 4.4.

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load_balancer()

1

2

3

4

5

6

15

1,

20

2,

15

. 4.4.

load_balance () , , , .

load _ba la nc e () find_bu si est _queu e () . . , 25% , , f ind_busiest_queue () NULL

load_balance (). .

load_balance () , . , , , (.. , not "cache hot"). , , .

load_balance () ,

( ), , .

, , . , , pu l l _ t a s k () .

, . , , load_balance ().

4

5

6

20

1

2

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load_balance (), ,

.

static int load_balance(int this_cpu, runqueue_t *this_rq,

struct sched_doraain *sd, enum idle_type idle)

{

struct sched_group *group;

runqueue_t *busiest;

unsigned long imbalance;

int nr_moved;

spin_lock(&this_rq>lock);

group = find_busiest_group(sd, this_cpu, &imbalance, idle);

if (!group)

goto out_balanced;

busiest = find_busiest_queue(group) ;

if (!busiest)

goto out_balanced;

nr_moved = 0;

if (busiest>nr_running > 1) {

double_lock_balance(this_rq, busiest);

nr_moved = move_tasks(this_rq, this_cpu, busiest,

imbalance, sd, idle);

spin_unlock(&busiest>lock);

}

spin_unlock(&this rq>lock);

if (!nr_moved) {

sd>nr_balance_failed++;

if (unlikely(sd>nr_balance_failed > sd>cache_nice_tries+2)) {

int wake = 0;

spin_lock(abusiest>lock);

if (!busiest>active_balance) {busiest>active_balance = 1;

busiest>push_cpu = this_cpu;

wake = 1;

}

spin_unlock(&busiest>lock);

if (wake)

wake_up_process(busiest>migration_thread);

sd>nr_balance_failed = sd>cache_nice_tries;

)

} elsesd>nr_balance_failed = 0;

sd>balance_interval = sd>min_interval;

return nr_moved;

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out_balanced:

spin_unlock (&this_rq>lock) ;

if (sd>balance_interval < sd>max_interval)

sd>balance_interval *=2;

return 0;}

,

. context_switch(), kernel/sched.. schedule (), .

. switch_mm (), include/asm/

mmu_context.h .

s wi tch_to () , i n c l ud e /asm/system.h, .

.

, schedule (). , , . need_resched , , schedule () (. 4.2). schediiler_tick (), , try_to_wake_up (), , , . , , schedule () . , , .

4.2. n e e d _ r e s c h e d

set_tsk_need_resched (task) need_resched

clear_tsk_need_resched (task) need_resched

need_resched() need_resched . t rue,

, fa lse,

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, need_resched . , , .

, , ( current , ). , 2.2. 2.2 2.4 task_struct int. 2.6 thread info. ,

.

(user preemption)

, , need_resched , , . ,

"" . , , .

, need_resched. , , . ,

entry.S ( , , ). , .

.

.

Linux, Unix, (, preemptible). . , , , . , ( ) . 2.6, Linux : , , ,

. ?

, ,

7/26/2019 . Linux 2006

91/451

. ,

, .

(SMPsafe), ,

.

, ,

preempt_count thread_inf

.

,

.

. ,

, need_resched

preempt_count. need_resched

preempt__count , ,

. .

preempt_count , ,

.

.

, ,

preempt_count . ,

, , need_r esched.

, .

,

9.

,

schedule () .

,

, ,

. ,

schedule (), , .

.

.

.

, , schedule ().

, ,

, .. ( schedule ()).

Linux

(reallime): SCHED_FIFO SCHED_RR.

SCHED_OTHER , ..

. SCHED_FIFO

" " (firstinfirstout, FIFO) .

SCHED_FIFO

SCHED_OTHER.

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sched_get_priority__min () . (MAX_USER_RT_PRIO1), 1.

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set_user_nice (), s tat ic_pr ia prio task_struct.

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unsigned long *dst, unsigned long len)

}

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unsigned long buf;

/* ,

, */

if (len != sizeof(buf))

return EINVAL;

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if (copy_from_user (&buf, src, len))

return EFAULT;

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*/

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return EFAULT;

/* */

return len;

}

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entry.S .

ENTRY(sys_call_table)

.long sys_restart_syscall /* 0 */

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...

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/*

* This file contains the system call numbers.

*/

#define __NR_restart_syscall 0

#define __NR_exit 1

#define __NR_fork 2

#define __NR_read 3

#define __HR_write 4

#define __NR_open 5

...

#define __NR_mq_unlink 278

#define __NR_mq_timedsend 279

#define __NR_mq_timedreceive 280

#define __NR_mq_notify 281#define __NR_mq_getsetattr 282

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.

#define __NR_foo 283

f ().

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{

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open (). 2 + 2*n .

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.

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, . NR_open, , .

, .

, , . , open ().

, , , .

#define NR_foo 283

__syscallO(long, foo)

int main ()

{

long stack_size;

stack_size = foo () ;

printf (" %ld\n", stack_size);

return 0;

}

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7/26/2019 . Linux 2006

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7/26/2019 . Linux 2006

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7/26/2019 . Linux 2006

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/* request_irq: */

int request_irq(unsigned int irq,

irqreturn_t (*handler)(int, void *, struct pt_regs *),

unsigned long irqflags,

const char * devname,

void *dev_id);

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, , , , , , , . (probing)

. , h a n d l e r ,

, . , . . irqreturn_t. .

, irqflags, .

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SA_INTERRUPT. , . , Linux ., , , , .

: . , . ( ) , , . , , .

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. . .

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, (cookie) ( ISA,, , ).

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. (

), , , , .

r eq uest_ i rq () . ,

. EBUSY, ,

( , SA_SHIRQ).

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.

if (request_irq(irqn, my_interrupt, SA_SHIRQ, "my_device", dev)){

printk(KERN_ERR "my_device: cannot register IRQ %d\n", irqn);

return EIO;

}

irqn , my_interrupt , , "my_device", dev dev_id. , , . , . . , , .

void free_irq(unsigned int irq, void *dev_id)

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, .

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, , , f ree_irq() . , devoid NULL, , .

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). , dev_id, , ,

request_irq () . , , , , . , () (device structure) , , , , dev_id .

, regs, , , . ,

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. , . , , .

irqreturn_t. : IRQ_NONE IRQ_HANDLED. , , , , . ,

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