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<p style="TEXT-ALIGN: center" align="center"><span style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman"><font color="#FFFFFF">分页存储管理方式的地址结构</font></span></p>
<p><font color="#FFFFFF"><span lang="EN-US"> </span><span style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">若给定一个逻辑地址空间中的地址为</span><span lang="EN-US">A</span><span style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">，页面的大小为</span><span lang="EN-US">L</span><span style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">，则页号</span><span lang="EN-US">P</span><span style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">和页内地址</span><span lang="EN-US">d</span><span style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">可按下式求得</span><span lang="EN-US"><sub><v:shapetype id=_x0000_t75 coordsize = "21600,21600"
o:preferrelative = "t" o:spt = "75" filled = "f" stroked = "f" path =
" m@4@5 l@4@11@9@11@9@5 xe">
<v:stroke joinstyle =
"miter">
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<v:formulas>
<v:f eqn =
"if lineDrawn pixelLineWidth 0 ">
</v:f>
<v:f eqn = "sum @0 1 0 ">
</v:f>
<v:f eqn =
"sum 0 0 @1 ">
</v:f>
<v:f eqn = "prod @2 1 2 ">
</v:f>
<v:f eqn =
"prod @3 21600 pixelWidth ">
</v:f>
<v:f eqn =
"prod @3 21600 pixelHeight ">
</v:f>
<v:f eqn = "sum @0 0 1 ">
</v:f>
<v:f eqn =
"prod @6 1 2 ">
</v:f>
<v:f eqn = "prod @7 21600 pixelWidth ">
</v:f>
<v:f eqn =
"sum @8 21600 0 ">
</v:f>
<v:f eqn = "prod @7 21600 pixelHeight ">
</v:f>
<v:f eqn =
"sum @10 21600 0 ">
</v:f>
</v:formulas>
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gradientshapeok = "t" o:connecttype = "rect">
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style="WIDTH: 62.25pt; HEIGHT: 30.75pt" o:ole="" type = "#_x0000_t75" coordsize
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<v:imagedata o:title="" src =
"./ch5.files/image001.wmz">
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</sub><span style="mso-spacerun: yes">
</span>d = A mod L</span></font></p>
<p><font color="#FFFFFF"><span style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">其中，</span><span lang="EN-US">INT</span><span style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">是整除函数，</span><span lang="EN-US">mod</span><span style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">是取余函数。</span></font></p>
<p><font color="#FFFFFF"><span style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">例如，其系统的页面大小为</span><span lang="EN-US">1KB</span><span style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">，设</span><span lang="EN-US">A=2170
H</span><span style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">，则由上式可以求得</span><span lang="EN-US">P</span><span style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">＝</span><span lang="EN-US">2</span><span style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">，</span><span lang="EN-US">d</span><span style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">＝</span><span lang="EN-US">122</span><span style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">。</span></font></p>
<p><font color="#FFFFFF"><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">二、页表</span><span lang="EN-US"><o:p>
</o:p>
</span></font></p>
<p style="TEXT-ALIGN: center" align="center"><font color="#FFFFFF"><span style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">页号</span><span style="mso-spacerun: yes" lang="EN-US">
</span><span style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">物理块号</span></font></p>
<table style="BORDER-RIGHT: medium none; BORDER-TOP: medium none; MARGIN-LEFT: 95.4pt; BORDER-LEFT: medium none; BORDER-BOTTOM: medium none; BORDER-COLLAPSE: collapse; mso-border-alt: solid windowtext .5pt; mso-padding-alt: 0cm 5.4pt 0cm 5.4pt" cellSpacing="0" cellPadding="0" border="1">
<tbody>
<tr>
<td style="BORDER-RIGHT: windowtext 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: windowtext 0.5pt solid; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: windowtext 0.5pt solid; WIDTH: 117.65pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 0.5pt solid" vAlign="top" width="157">
<p style="TEXT-ALIGN: center" align="center"><span lang="EN-US"><font color="#FFFFFF">0</font></span></p>
</td>
<td style="BORDER-RIGHT: windowtext 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: windowtext 0.5pt solid; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 107.35pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 0.5pt solid; mso-border-left-alt: solid windowtext .5pt" vAlign="top" width="143">
<p style="TEXT-ALIGN: center" align="center"><span lang="EN-US"><font color="#FFFFFF">10</font></span></p>
</td>
</tr>
<tr>
<td style="BORDER-RIGHT: windowtext 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: windowtext 0.5pt solid; WIDTH: 117.65pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 0.5pt solid; mso-border-top-alt: solid windowtext .5pt" vAlign="top" width="157">
<p style="TEXT-ALIGN: center" align="center"><span lang="EN-US"><font color="#FFFFFF">1</font></span></p>
</td>
<td style="BORDER-RIGHT: windowtext 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 107.35pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 0.5pt solid; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" vAlign="top" width="143">
<p style="TEXT-ALIGN: center" align="center"><span lang="EN-US"><font color="#FFFFFF">25</font></span></p>
</td>
</tr>
<tr>
<td style="BORDER-RIGHT: windowtext 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: windowtext 0.5pt solid; WIDTH: 117.65pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 0.5pt solid; mso-border-top-alt: solid windowtext .5pt" vAlign="top" width="157">
<p style="TEXT-ALIGN: center" align="center"><span lang="EN-US"><font color="#FFFFFF">2</font></span></p>
</td>
<td style="BORDER-RIGHT: windowtext 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 107.35pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 0.5pt solid; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" vAlign="top" width="143">
<p style="TEXT-ALIGN: center" align="center"><span lang="EN-US"><font color="#FFFFFF">34</font></span></p>
</td>
</tr>
<tr>
<td style="BORDER-RIGHT: windowtext 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: windowtext 0.5pt solid; WIDTH: 117.65pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 0.5pt solid; mso-border-top-alt: solid windowtext .5pt" vAlign="top" width="157">
<p style="TEXT-ALIGN: center" align="center"><span lang="EN-US"><font color="#FFFFFF">3</font></span></p>
</td>
<td style="BORDER-RIGHT: windowtext 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: medium none; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0cm; BORDER-LEFT: medium none; WIDTH: 107.35pt; PADDING-TOP: 0cm; BORDER-BOTTOM: windowtext 0.5pt solid; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" vAlign="top" width="143">
<p style="TEXT-ALIGN: center" align="center"><span lang="EN-US"><font color="#FFFFFF">54</font></span></p>
</td>
</tr>
</tbody>
</table>
<p><span lang="EN-US"><font color="#FFFFFF"> <o:p>
</o:p>
</font></span></p>
<p><font color="#FFFFFF"><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">三、页面大小的选择</span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt"><o:p>
</o:p>
</span></font></p>
<p><font color="#FFFFFF"><span style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">在确定地址结构时，若选择的页面较小，一方面可使内存碎片小，并减少了内存碎片的总空间、有利于提高内存利用串；但另一方面，也会使每个进程要求较多的页面，从而导致页表过长，占用大量内存；此外，还会降低页面换进换出的效率。若选择的页面较大，虽然可减少页表长度，提高换进换出效率，但却又会使页内碎片增大。因此。页面的大小应选得适中，通常页面的大小是</span><span lang="EN-US">2</span><span style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">的幂，且常在</span><span lang="EN-US">2<sup>9</sup></span><span style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">一</span><span lang="EN-US">2<sup>12</sup></span><span style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">之间，即在</span><span lang="EN-US">512</span><span style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">字节一</span><span lang="EN-US">4KB</span><span style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">之间。</span></font></p>
<p><font color="#FFFFFF"><span lang="EN-US"> </span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt">5．4．2地址变换机构<o:p>
</o:p>
</span></font></p>
<p style="MARGIN-LEFT: 24pt; TEXT-INDENT: -24pt; tab-stops: list 24.0pt; mso-list: l7 level1 lfo4"><font color="#FFFFFF"><span style="font-style: normal; font-variant: normal; font-weight: normal; mso-bidi-font-size: 10.0pt" lang="EN-US">一、
</span><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">基本的地址变换机构</span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt"><v:shape id=_x0000_i1026
style="WIDTH: 316.5pt; HEIGHT: 204.75pt" type = "#_x0000_t75" coordsize =
"21600,21600" fillcolor = "winColor(17)">
<v:imagedata o:title="图5-1" src =
"./ch5.files/image003.png">
</v:imagedata>
</v:shape>
<o:p>
</o:p>
</span></font></p>
<p><font color="#FFFFFF"><span style="mso-bidi-font-size: 10.0pt; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">二、具有快表的地址变换机构</span><span lang="EN-US"> <o:p>
</o:p>
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