ch27.mht

如果想学习操作系统

size=3D3>=B4=E6=B4=A2=C7=F8</FONT><FONT face=3D=CB=CE=CC=E5 =
color=3D#000000=20
            =
size=3D3>=C0=B4=BD=F8=D0=D0=CD=A8=D0=C5=A3=AC=BF=C9=B7=D6<BR>=CE=AA</FONT=
><FONT face=3D=CB=CE=CC=E5 color=3D#ff0080=20
            =
size=3D3>=B9=B2=CF=ED=CA=FD=BE=DD=BD=E1=B9=B9=B7=BD=CA=BD</FONT><FONT =
face=3D=CB=CE=CC=E5 color=3D#000000=20
            size=3D3>=A1=A2</FONT><FONT face=3D=CB=CE=CC=E5 =
color=3D#ff0080=20
            =
size=3D3>=B9=B2=CF=ED=B4=E6=B4=A2=C7=F8=B7=BD=CA=BD</FONT><FONT =
face=3D=CB=CE=CC=E5 color=3D#000000=20
        size=3D3>=A3=BB</FONT></TD></TR>
        <TR>
          <TD width=3D"19%" bgColor=3D#fce3c2>
            <DIV align=3Dcenter>
            <CENTER><PRE><FONT face=3D=CB=CE=CC=E5 color=3D#000000 =
size=3D3><STRONG>=CF=FB=CF=A2=CD=A8=D0=C5=B7=BD=CA=BD</STRONG></FONT></PR=
E></CENTER></DIV></TD>
          <TD width=3D"81%" bgColor=3D#aaf9a8><FONT face=3D=CB=CE=CC=E5 =
size=3D3><FONT=20
            =
color=3D#000000>=BD=F8=B3=CC=BC=E4=B5=C4=CF=FB=CF=A2=BD=BB=BB=BB=D2=D4</F=
ONT><FONT color=3D#0000ff><A=20
            =
href=3D"http://oa.gdut.edu.cn/os/multimedia/oscai/chapter2/pages/ch27.htm=
#=B8=C5=C4=EE">=CF=FB=CF=A2</A></FONT><FONT=20
            color=3D#000000>=BB=F2</FONT><FONT =
color=3D#ff0080>=B1=A8=CE=C4</FONT></FONT><FONT=20
            face=3D=CB=CE=CC=E5 color=3D#000000 =
size=3D3>=CE=AA=B5=A5=CE=BB=A3=AC=B3=CC=D0=F2=D4=B1=C0=FB=D3=C3=D2=BB=D7=E9=
=CD=A8=D0=C5=C3=FC=C1=EE<BR></FONT><FONT face=3D=CB=CE=CC=E5=20
            =
size=3D3>=A3=A8=D4=AD=D3=EF=A3=A9=C0=B4=CA=B5=CF=D6=CD=A8=D0=C5=A3=AC=BF=C9=
=B7=D6=CE=AA<FONT color=3D#ff0080>=D6=B1=BD=D3</FONT>=A1=A2<FONT=20
            =
color=3D#ff0080>=BC=E4=BD=D3=CD=A8=D0=C5=B7=BD=CA=BD</FONT>=A3=BB</FONT><=
/TD></TR>
        <TR>
          <TD width=3D"19%" bgColor=3D#fce3c2>
            <DIV align=3Dcenter>
            <CENTER><PRE><FONT face=3D=CB=CE=CC=E5 color=3D#000000 =
size=3D3><STRONG>=B9=B2=CF=ED=CE=C4=BC=FE=B7=BD=CA=BD</STRONG></FONT></PR=
E></CENTER></DIV></TD>
          <TD width=3D"81%" bgColor=3D#aaf9a8><FONT face=3D=CB=CE=CC=E5 =
color=3D#000000=20
            size=3D3>=C0=FB=D3=C3</FONT><FONT face=3D=CB=CE=CC=E5 =
color=3D#ff0080 size=3D3>=B9=B2=CF=ED=CE=C4=BC=FE</FONT><FONT=20
            face=3D=CB=CE=CC=E5 color=3D#000000=20
      =
size=3D3>=C0=B4=CA=B5=CF=D6=BD=F8=B3=CC=BC=E4=B5=C4=CD=A8=D0=C5=A3=BB</FO=
NT></TD></TR></TBODY></TABLE></CENTER></DIV><PRE><FONT =
face=3D=CB=CE=CC=E5 color=3D#000000 size=3D3>        =
</FONT><STRONG><FONT face=3D=CB=CE=CC=E5 color=3D#ff0000 =
size=3D3>=A1=F7</FONT></STRONG><FONT face=3D=CB=CE=CC=E5 color=3D#000000 =
size=3D3>=D4=DA<STRONG>UNIX=CF=B5=CD=B3</STRONG>=D6=D0=A3=AC=C0=FB=D3=C3=D2=
=BB=B8=F6=B4=F2=BF=AA=B5=C4</FONT><FONT face=3D=CB=CE=CC=E5 =
color=3D#ff0080 size=3D3>=B9=B2=CF=ED=CE=C4=BC=FE</FONT><FONT =
face=3D=CB=CE=CC=E5 color=3D#000000 =
size=3D3>=C0=B4=C1=AC=BD=D3=C1=BD=B8=F6=CF=E0=BB=A5=CD=A8=D0=C5=B5=C4=BD=F8=
=B3=CC=A3=AC=B8=C3=B9=B2=CF=ED=CE=C4=BC=FE=B3=C6=CE=AA</FONT></PRE><PRE><=
FONT face=3D=CB=CE=CC=E5 color=3D#000000 size=3D3>          </FONT><FONT =
face=3D=CB=CE=CC=E5 color=3D#ff0080 =
size=3D3>=B9=DC=B5=C0=A3=A8Pipe=A3=A9</FONT><FONT face=3D=CB=CE=CC=E5 =
color=3D#000000 =
size=3D3>=A3=AC=D2=F2=B6=F8=B8=C3=B7=BD=CA=BD=D3=D6=B3=C6=CE=AA</FONT><FO=
NT face=3D=CB=CE=CC=E5 color=3D#ff0080 =
size=3D3>=B9=DC=B5=C0=CD=A8=D0=C5</FONT><FONT face=3D=CB=CE=CC=E5 =
color=3D#000000 size=3D3>=A1=A3</FONT></PRE><PRE><FONT =
face=3D=CB=CE=CC=E5 color=3D#000000 size=3D3>        </FONT><FONT =
face=3D=CB=CE=CC=E5 color=3D#ff0000 =
size=3D3><STRONG>=A1=F7</STRONG></FONT><FONT face=3D=CB=CE=CC=E5 =
color=3D#000000 =
size=3D3>=CE=AA=C1=CB=D0=AD=B5=F7=CB=AB=B7=BD=CD=A8=D0=C5=A3=AC</FONT><FO=
NT face=3D=CB=CE=CC=E5 color=3D#ff0080 =
size=3D3>=B9=DC=B5=C0=CD=A8=D0=C5</FONT><FONT face=3D=CB=CE=CC=E5 =
color=3D#000000 =
size=3D3>=B1=D8=D0=EB=CC=E1=B9=A9=C8=FD=B7=BD=C3=E6=B5=C4=D0=AD=B5=F7=C4=DC=
=C1=A6=A3=BA</FONT><FONT face=3D=CB=CE=CC=E5 color=3D#ff0080 =
size=3D3>=BB=A5=B3=E2</FONT><FONT face=3D=CB=CE=CC=E5 color=3D#000000 =
size=3D3>=A1=A2</FONT><FONT face=3D=CB=CE=CC=E5 color=3D#ff0080 =
size=3D3>=CD=AC=B2=BD</FONT><FONT face=3D=CB=CE=CC=E5 color=3D#000000 =
size=3D3>=A1=A2</FONT><FONT face=3D=CB=CE=CC=E5 color=3D#ff0080 =
size=3D3>=B6=D4=B7=BD=CA=C7=B7=F1=B4=E6=D4=DA</FONT><FONT =
face=3D=CB=CE=CC=E5 color=3D#000000 =
size=3D3>=A1=A3</FONT></PRE></TD></TR></TBODY></TABLE>
<TABLE cellSpacing=3D0 cellPadding=3D0 width=3D"98%" border=3D0>
  <TBODY>
  <TR>
    <TD width=3D"100%">
      <P align=3Dright><A =
name=3D=B7=BD=CA=BD=BC=B0=CA=B5=C0=FD></A><!--webbot bot=3D"ImageMap" =
rectangle=3D"(1,3) (144,32) #%e9%a1%b5%e5%a4%b4" =
src=3D"../images/Backhead.gif" border=3D"0" alt=3D"Backhead.gif (2500 =
bytes)" startspan --><MAP=20
      name=3DFrontPageMap5><AREA shape=3DRECT coords=3D1,3,144,32=20
        =
href=3D"http://oa.gdut.edu.cn/os/multimedia/oscai/chapter2/pages/ch27.htm=
#=D2=B3=CD=B7"></MAP><A=20
      =
href=3D"http://oa.gdut.edu.cn/os/multimedia/oscai/_vti_bin/shtml.dll/chap=
ter2/pages/ch26.htm/map5"><IMG=20
      height=3D33 alt=3D"Backhead.gif (2500 bytes)" isMap=20
      =
src=3D"http://oa.gdut.edu.cn/os/multimedia/oscai/chapter2/images/Backhead=
.gif"=20
      width=3D145 useMap=3D#FrontPageMap5 border=3D0></A><!--webbot =
bot=3D"ImageMap" endspan i-checksum=3D"21032" =
--></P></TD></TR></TBODY></TABLE>
<TABLE cellSpacing=3D0 cellPadding=3D0 width=3D"98%" border=3D0>
  <TBODY>
  <TR>
    <TD width=3D"100%"><PRE><IMG height=3D25 =
src=3D"http://oa.gdut.edu.cn/os/multimedia/oscai/chapter2/images/eyeball.=
gif" width=3D25><STRONG><FONT face=3D=CB=CE=CC=E5 color=3D#ff0000 =
size=3D3> </FONT><FONT face=3D=CB=CE=CC=E5 color=3D#e74914 =
size=3D5>=D6=B1</FONT><FONT face=3D=CB=CE=CC=E5 color=3D#000000 =
size=3D4>=BD=D3=CD=A8=D0=C5=B7=BD=CA=BD=BC=B0=CA=B5=C0=FD</FONT></STRONG>=
<IMG height=3D21 =
src=3D"http://oa.gdut.edu.cn/os/multimedia/oscai/chapter2/images/arrow1.G=
IF" width=3D62></PRE></TD></TR>
  <TR>
    <TD width=3D"100%"><PRE><FONT face=3D=CB=CE=CC=E5 color=3D#000000 =
size=3D3>        </FONT><IMG height=3D29 =
src=3D"http://oa.gdut.edu.cn/os/multimedia/oscai/chapter2/images/=D4=DA.G=
IF" width=3D29><FONT face=3D=CB=CE=CC=E5 color=3D#000000 =
size=3D3>=C9=CF=CA=F6=BC=B8=D6=D6=CD=A8=D0=C5=B7=BD=CA=BD=D6=D0=A3=AC</FO=
NT><FONT face=3D=CB=CE=CC=E5 color=3D#ff0080 =
size=3D3>=D6=B1=BD=D3=CD=A8=D0=C5=B7=BD=CA=BD</FONT><FONT =
face=3D=CB=CE=CC=E5 color=3D#000000 size=3D3>=D2=D4</FONT><FONT =
face=3D=CB=CE=CC=E5 color=3D#ff0080 =
size=3D3>=C4=DA=B4=E6=BB=BA=B3=E5=C7=F8</FONT><FONT face=3D=CB=CE=CC=E5 =
color=3D#000000 =
size=3D3>=CE=AA=BB=F9=B4=A1=A3=AC=B9=CA=D3=D0=BD=CF=B8=DF=B5=C4=CD=A8=D0=C5=
=CB=D9=B6=C8=A3=AC=CB=FC=D2=D1=B3=C9=CE=AA</FONT></PRE><PRE><FONT =
face=3D=CB=CE=CC=E5 color=3D#000000 size=3D3>    </FONT><FONT =
face=3D=CB=CE=CC=E5 color=3D#ff0080 =
size=3D3>=B5=A5=B4=A6=C0=ED=BB=FA=B6=E0=B5=C0=B3=CC=D0=F2=CF=B5=CD=B3</FO=
NT><FONT face=3D=CB=CE=CC=E5 color=3D#000000 =
size=3D3>=D6=D0=D7=EE=C1=F7=D0=D0=B5=C4=D2=BB=D6=D6=CD=A8=D0=C5=B7=BD=CA=BD=
=A1=A3</FONT></PRE><PRE><FONT face=3D=CB=CE=CC=E5 color=3D#000000 =
size=3D3>    </FONT><IMG height=3D15 alt=3D"=C8=FD=BD=C7=BC=FD=CD=B7.GIF =
(188 bytes)" =
src=3D"http://oa.gdut.edu.cn/os/multimedia/oscai/chapter2/images/angle.GI=
F" width=3D14><FONT face=3D=CB=CE=CC=E5 color=3D#800080 =
size=3D3><STRONG>=D6=B1=BD=D3=CD=A8=D0=C5=B7=BD=CA=BD=C4=A3=D0=CD=CD=BC</=
STRONG></FONT></PRE>
      <DIV align=3Dcenter>
      <CENTER><PRE><IMG height=3D215 =
src=3D"http://oa.gdut.edu.cn/os/multimedia/oscai/chapter2/images/ch2601.G=
IF" width=3D526></PRE></CENTER></DIV><PRE><FONT face=3D=CB=CE=CC=E5 =
color=3D#000000 size=3D3>    </FONT><IMG height=3D15 =
src=3D"http://oa.gdut.edu.cn/os/multimedia/oscai/chapter2/images/angle.GI=
F" width=3D14><FONT face=3D=CB=CE=CC=E5 color=3D#800080 =
size=3D3><STRONG>=D6=B1=BD=D3=CD=A8=D0=C5=B7=BD=CA=BD=CA=B5=C0=FD--=CF=FB=
=CF=A2=BB=BA=B3=E5=CD=A8=D0=C5</STRONG></FONT></PRE><PRE><FONT =
face=3D=CB=CE=CC=E5 color=3D#000000 size=3D3>        </FONT><IMG =
height=3D16 =
src=3D"http://oa.gdut.edu.cn/os/multimedia/oscai/chapter2/images/LBLUEP2.=
GIF" width=3D16><FONT face=3D=CB=CE=CC=E5 color=3D#000000 =
size=3D3>=CF=FB=CF=A2=BB=BA=B3=E5=CA=FD=BE=DD=BD=E1=B9=B9</FONT></PRE>
      <DIV align=3Dcenter>
      <CENTER>
      <TABLE cellSpacing=3D0 cellPadding=3D0 width=3D"68%" border=3D0>
        <TBODY>
        <TR>
          <TD width=3D"21%" rowSpan=3D4>
            <TABLE cellSpacing=3D1 width=3D"96%" border=3D1>
              <TBODY>
              <TR>
                <TD width=3D"100%" bgColor=3D#fce3c2>
                  <P align=3Dcenter><FONT face=3D=CB=CE=CC=E5 =
color=3D#000000=20
                  size=3D3><STRONG>sender</STRONG></FONT></P></TD></TR>
              <TR>
                <TD width=3D"100%" bgColor=3D#fce3c2>
                  <P align=3Dcenter><FONT face=3D=CB=CE=CC=E5 =
color=3D#000000=20
                  size=3D3><STRONG>size</STRONG></FONT></P></TD></TR>
              <TR>
                <TD width=3D"100%" bgColor=3D#fce3c2>
                  <P align=3Dcenter><FONT face=3D=CB=CE=CC=E5 =
color=3D#000000=20
                  size=3D3><STRONG>text</STRONG></FONT></P></TD></TR>
              <TR>
                <TD width=3D"100%" bgColor=3D#fce3c2>
                  <P align=3Dcenter><FONT face=3D=CB=CE=CC=E5 =
color=3D#000000=20
                  =
size=3D3><STRONG>next</STRONG></FONT></P></TD></TR></TBODY></TABLE></TD>
          <TD width=3D"79%"><FONT face=3D=CB=CE=CC=E5 color=3D#000000 =
size=3D3>&nbsp;=20
            =CF=FB=CF=A2=B7=A2=CB=CD=D5=DF</FONT></TD></TR>
        <TR>
          <TD width=3D"79%"><FONT face=3D=CB=CE=CC=E5 color=3D#000000 =
size=3D3>&nbsp;=20
          =CF=FB=CF=A2=B3=A4=B6=C8</FONT></TD></TR>
        <TR>
          <TD width=3D"79%"><FONT face=3D=CB=CE=CC=E5 color=3D#000000 =
size=3D3>&nbsp;=20
          =CF=FB=CF=A2=D5=FD=CE=C4</FONT></TD></TR>
        <TR>
          <TD width=3D"79%"><FONT face=3D=CB=CE=CC=E5 color=3D#000000 =
size=3D3>&nbsp;=20
            =
=D6=B8=CF=F2=CF=C2=D2=BB=B8=F6=CF=FB=CF=A2=BB=BA=B3=E5=C7=F8=B5=C4=D6=B8=D5=
=EB</FONT></TD></TR></TBODY></TABLE></CENTER></DIV><PRE><FONT =
face=3D=CB=CE=CC=E5 color=3D#000000 size=3D3>          =
=B4=CB=CD=E2=A3=AC=BD=F8=B3=CC=B5=C4PCB=BF=E9=D6=D0=D4=F6=BC=D3=D2=BB=D0=A9=
=CA=FD=BE=DD=CF=EE=D2=D4=D6=A7=B3=D6=CF=FB=CF=A2=BB=BA=B3=E5=C7=F8=B5=C4=CD=
=A8=D0=C5=BB=FA=D6=C6=CA=B5=CF=D6=A3=BB</FONT></PRE><PRE><FONT =
face=3D=CB=CE=CC=E5 color=3D#000000 size=3D3>          =
=C8=E7=A3=BAmq=A3=AC=CF=FB=CF=A2=C1=B4=CA=D7=D6=B8=D5=EB=A3=BBmutex=A3=AC=
=CF=FB=CF=A2=C1=B4=BB=A5=B3=E2=D0=C5=BA=C5=C1=BF=A3=BBSm=A3=AC=CF=FB=CF=A2=
=C1=B4=CD=AC=B2=BD=BC=C6=CA=FD=D0=C5=BA=C5=C1=BF=A1=A3</FONT></PRE><PRE><=
FONT face=3D=CB=CE=CC=E5 color=3D#000000 size=3D3>        </FONT><IMG =
height=3D16 =
src=3D"http://oa.gdut.edu.cn/os/multimedia/oscai/chapter2/images/LFUCHS~1=
.GIF" width=3D16><FONT face=3D=CB=CE=CC=E5 color=3D#000000 =
size=3D3>=C1=BD=B8=F6=BD=F8=B3=CC=C0=FB=D3=C3=CF=FB=CF=A2=BB=BA=B3=E5=C7=F8=
=CD=A8=D0=C5=B5=C4=B9=FD=B3=CC</FONT></PRE>
      <DIV align=3Dcenter>
      <CENTER><PRE><IMG height=3D330 =
src=3D"http://oa.gdut.edu.cn/os/multimedia/oscai/chapter2/images/ch2602.G=
IF" width=3D373></PRE></CENTER></DIV><PRE><FONT face=3D=CB=CE=CC=E5 =
color=3D#000000 size=3D3>        </FONT><IMG height=3D16 =
src=3D"http://oa.gdut.edu.cn/os/multimedia/oscai/chapter2/images/LREDP.GI=
F" width=3D16><FONT face=3D=CB=CE=CC=E5 color=3D#000000 =
size=3D3>=CD=A8=D0=C5=D4=AD=D3=EF</FONT></PRE></TD></TR></TBODY></TABLE>
<TABLE cellSpacing=3D0 cellPadding=3D0 width=3D"98%" border=3D0>
  <TBODY>
  <TR>
    <TD width=3D"48%"><PRE><FONT face=3D=CB=CE=CC=E5 color=3D#000000 =
size=3D3>          </FONT><FONT face=3D=CB=CE=CC=E5 color=3D#ff0080 =
size=3D3><STRONG>=B7=A2=CB=CD=D4=AD=D3=EF</STRONG></FONT></PRE></TD>