操作系统作业4姓名,学号Word格式.docx

操作系统作业4姓名,学号Word格式.docx

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stdio.h>

#include<

unistd.h>

int main（）

｛

int i;

for （i一O;

i<

4;

i++）

fork（）;

｝

returnO;

Figure1:

ProgramforQuestion3.

2

16processesarecreated.

Hint:

YoumayincludeprintfOstatementstobetterunderstandbowmanyprocesseshavebeencreated.

4..Explainthecircumstancesunderwhichthelineofcodemarkedprintf（"

LINEJ"

）inFigure2willbereached

#include<

sys/types.h>

#include<

stdio.h>

unistd.h>

int main（）

pid_t pid;

I*forkachildprocess*Ipid=fork（）;

if （pid<

O）{I*erroroccurred*Ifprintf（stderr,"

ForkFailed"

）;

return1;

elseif （pid==0） { I*childprocess*I

execlp（"

/bin/ls"

"

ls"

NULL）;

printf（"

LINEJ"

）;

else{/*parentprocess*I

I*parentwillw吐t for the childtocomplete*I

w吐t（NULL）;

printf（"

ChildComplete"

Fi驴re2:

ProgramforQuestion4.

橾作系统课柱作业

3

ThecalltoexecOreplacestheaddressspaceoftheprocesswiththeprogramspecifiedastheparametertoexecQ.IfthecalltoexecOsucceeds,thenewprogramisnowrunningandcontrolfromthecalltoexec（）neverreturns.ltithisscenario,thelineprintf（"

LineJ"

wouldneverbeperformed.However,ifanerroroccmsinthecalltoexecO,thefunctionren1rnscontrolandthereforthelineprintf（"

）;

wouldbeperformed.

5.UsingtheprograminFigure3,identifythevaluesofpidat1inesA,B,C,andD.（Assumethattheactualpidsoftheparentandchildare2600and2603,respectively.）

#includes<

ys/types.h>

stdio.h>

unistd.h>

intmain{）

picLtpid,pidl;

I*forkachildprocess寒／pid frok（）;

0）{/•erroroccurred•/fprintf（stderr,"

ForkFaile心）；

elseif（pidsc 0）{/•childprocess•/pidl•getpid（）;

printf（"

child:

pid=¼

d"

pid）;

/亭A*Iprintf（"

child:

pid1=¼

p过1）;

/•B•I

else{/•parentprocess•/pidl=getpid（）;

parent:

pid=i.d"

/拿C拿／printf（"

p工di•i.d"

pidl）;

/*D•I11ait（NULL）;

returnO;

Figure3:

ProgramforQuestion5.

A=0,B=2603,C=260,3D=2600

4

6.UsingtheprogramshowninFigure4,explainwhattheoutputwillbeat

linesXandY.

芍s/types.h>

#include<

#defineSIZE5

int nums[SIZE]={0,1,2,3,4};

inti;

pid=fork（）;

if （pid=0）{

for （i=O;

i<

SIZE;

i++）{

nums［i] •=-i;

printf（"

CHILD:

%d11,nums [i]）;

/•LINEX•/

elseif （pid>

0）{

wait（NULL）;

for （i =O;

i++）

rpintf（"

PARENT:

加 "

nums[i]）;

I*LINEY•/

Figure4:

ProgramforQuestion6.

Becausethechildisacopyoftheparent,anychangesthechildmakeswilloccurinitscopyofthedataandwon'

tbereflectedintheparent.Asaresult,thevaluesoutputbythechildatlineXare0,-1,-4,-9,-16.ThevaluesoutputbytheparentatlineYare0,I,2,3,4

5

操作系统课杠作业

7.Whichofthefollowingcomponentsofprogramstatearesharedacrossthreadsinamultithreadedprocess?

a.Registervalues

b.Heapmemory

c.Globalvariables

d.Stackmemory

Thethreadsofamultithreadedprocessshareheapmemoryandglobalvariables.Eachthreadhasitsseparatesetofregistervaluesandaseparatestack.

8.Asystemwithtwodual-coreprocessorshasfourprocessorsavailableforscheduling.ACPU-intensiveapplicationisrunningonthissystem.Allinputisperformed