chapter6.htm

mips run 中文版

style="FONT-FAMILY: SimSun; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">倍以容纳</SPAN>2<SPAN 
lang=ZH-CN 
style="FONT-FAMILY: SimSun; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">个各自映射独立物理页的连续的</SPAN>VPN<SPAN 
lang=ZH-CN 
style="FONT-FAMILY: SimSun; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">。这种成对的入口仅增添了很少的硬件逻辑但却加倍了</SPAN>TLB<SPAN 
lang=ZH-CN 
style="FONT-FAMILY: SimSun; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">可以装入的映射页，避免了对</SPAN>TLB<SPAN 
lang=ZH-CN 
style="FONT-FAMILY: SimSun; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">的设计进行大幅度的调整。</SPAN></P>
<P class=MsoNormal style="MARGIN-LEFT: 21pt">&nbsp;<O:P> </O:P></P>
<P class=MsoNormal style="MARGIN-LEFT: 21pt"><SPAN 
style="mso-tab-count: 1">&nbsp;&nbsp;&nbsp;&nbsp; </SPAN><SPAN lang=ZH-CN 
style="FONT-FAMILY: SimSun; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">您可以看到为何被称为“全相连”，这强调了所有的键值实际上是并行对输入值进行比较的。</SPAN></P>
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align=center><IMG height=123 src="" width=459 v:shapes="_x0000_i1028"></P>
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align=center><B><SPAN lang=ZH-CN 
style="FONT-FAMILY: SimSun; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">图</SPAN>6.3</B></P>
<P class=MsoNormal style="MARGIN-LEFT: 21pt"><SPAN 
style="mso-tab-count: 1">&nbsp;&nbsp;&nbsp;&nbsp; </SPAN>TLB<SPAN lang=ZH-CN 
style="FONT-FAMILY: SimSun; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">的入口如图</SPAN>6-3<SPAN 
lang=ZH-CN 
style="FONT-FAMILY: SimSun; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">中所示（您可以在后面的</SPAN>6.5<SPAN 
lang=ZH-CN 
style="FONT-FAMILY: SimSun; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">节中找到其详细的编程信息）。</SPAN>TLB<SPAN 
lang=ZH-CN 
style="FONT-FAMILY: SimSun; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">的键值包含了以下内容：</SPAN></P>
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style="MARGIN-LEFT: 63pt; TEXT-INDENT: -21pt; mso-list: l12 level1 lfo7; tab-stops: list 63.0pt"><SPAN 
style="FONT-FAMILY: Wingdings">n<SPAN 
style="FONT: 7pt 'Times New Roman'">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
</SPAN></SPAN><B>VPN</B><SPAN lang=ZH-CN 
style="FONT-FAMILY: SimSun; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">：虚地址的高位（即虚页地址）。在双入口</SPAN>TLB<SPAN 
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style="FONT-FAMILY: SimSun; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">内被称作</SPAN>VPN2<SPAN 
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style="FONT-FAMILY: SimSun; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">，这是为了强调如果每个物理页都是</SPAN>4KB<SPAN 
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style="FONT-FAMILY: SimSun; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">，那么一个虚地址将会去掉低位（这些低位用来选择左边的输出域或右边的输出域）来进行比较以选出一对入口。</SPAN></P>
<P class=MsoNormal 
style="MARGIN-LEFT: 63pt; TEXT-INDENT: -21pt; mso-list: l12 level1 lfo7; tab-stops: list 63.0pt"><SPAN 
style="FONT-FAMILY: Wingdings">n<SPAN 
style="FONT: 7pt 'Times New Roman'">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
</SPAN></SPAN><B>PageMask</B><SPAN lang=ZH-CN 
style="FONT-FAMILY: SimSun; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">：这只有近来的</SPAN>CPU<SPAN 
lang=ZH-CN 
style="FONT-FAMILY: SimSun; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">才有。它用来控制使用虚地址的多少位来跟</SPAN>VPN<SPAN 
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style="FONT-FAMILY: SimSun; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">进行比较并决定多少位被通过后加入实地址；使用越少的位达成的匹配映射的空间越大。</SPAN>MIPS 
CPU<SPAN lang=ZH-CN 
style="FONT-FAMILY: SimSun; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">能够设置一个入口映射最大达</SPAN>16MB<SPAN 
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style="FONT-FAMILY: SimSun; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">的内存。在使用各种页大小的情况下，都是用被掩位中的最高位来选中奇数号或偶数号入口。</SPAN></P>
<P class=MsoNormal 
style="MARGIN-LEFT: 63pt; TEXT-INDENT: -21pt; mso-list: l12 level1 lfo7; tab-stops: list 63.0pt"><SPAN 
style="FONT-FAMILY: Wingdings; mso-bidi-font-weight: bold">n<SPAN 
style="FONT: 7pt 'Times New Roman'">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
</SPAN></SPAN><B>ASID</B><SPAN lang=ZH-CN 
style="FONT-FAMILY: SimSun; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">：标记这个转译过程属于某一个特定进程，因此除非</SPAN>CPU<SPAN 
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style="FONT-FAMILY: SimSun; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">的当前</SPAN>ASID<SPAN 
lang=ZH-CN 
style="FONT-FAMILY: SimSun; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">与之相吻合，否则匹配是不会成功的。“</SPAN>C<SPAN 
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style="FONT-FAMILY: SimSun; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">”这一位如果被置起为</SPAN>1<SPAN 
lang=ZH-CN 
style="FONT-FAMILY: SimSun; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">，则关闭</SPAN>ASID<SPAN 
lang=ZH-CN 
style="FONT-FAMILY: SimSun; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">的匹配，这标志着本转译可以在所有的进程空间内进行（因此地址映射中的这一部分是被所有空间共享的），</SPAN>ASID<SPAN 
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style="FONT-FAMILY: SimSun; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">位在早期</SPAN>CPU<SPAN 
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style="FONT-FAMILY: SimSun; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">中为</SPAN>6<SPAN 
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style="FONT-FAMILY: SimSun; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">位长度，而在近期的</SPAN>CPU<SPAN 
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style="FONT-FAMILY: SimSun; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">中则为</SPAN>8<SPAN 
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style="FONT-FAMILY: SimSun; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">位。</SPAN><B><O:P> 
</O:P></B></P>
<P class=MsoNormal style="MARGIN-LEFT: 63pt">TLB<SPAN lang=ZH-CN 
style="FONT-FAMILY: SimSun; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">的输出部将会给出物理页号和一批数量不大但足够使用的标志位。</SPAN></P>
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style="MARGIN-LEFT: 63pt; TEXT-INDENT: -21pt; mso-list: l12 level1 lfo7; tab-stops: list 63.0pt"><SPAN 
style="FONT-FAMILY: Wingdings; mso-bidi-font-weight: bold">n<SPAN 
style="FONT: 7pt 'Times New Roman'">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
</SPAN></SPAN><B><SPAN lang=ZH-CN 
style="FONT-FAMILY: SimSun; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">物理页号（</SPAN>PFN<SPAN 
lang=ZH-CN 
style="FONT-FAMILY: SimSun; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">）：</SPAN></B>32<SPAN 
lang=ZH-CN 
style="FONT-FAMILY: SimSun; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">位的</SPAN>CPU<SPAN 
lang=ZH-CN 
style="FONT-FAMILY: SimSun; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">仅仅有一个</SPAN>N<SPAN 
lang=ZH-CN 
style="FONT-FAMILY: SimSun; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">（</SPAN>noncacheable<SPAN 
lang=ZH-CN 
style="FONT-FAMILY: SimSun; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">，不可缓存）位——</SPAN>0<SPAN 
lang=ZH-CN 
style="FONT-FAMILY: SimSun; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">表示</SPAN>&shy;<SPAN 
lang=ZH-CN 
style="FONT-FAMILY: SimSun; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">可以缓存，</SPAN>1<SPAN 
lang=ZH-CN 
style="FONT-FAMILY: SimSun; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">表示不可缓存。</SPAN><B><O:P> 
</O:P></B></P>
<P class=MsoNormal style="MARGIN-LEFT: 63pt"><SPAN lang=ZH-CN 
style="FONT-FAMILY: SimSun; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">而</SPAN>64<SPAN 
lang=ZH-CN 
style="FONT-FAMILY: SimSun; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">位</SPAN>CPU<SPAN 
lang=ZH-CN 
style="FONT-FAMILY: SimSun; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">则提供了一个</SPAN>3<SPAN 
lang=ZH-CN 
style="FONT-FAMILY: SimSun; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">位的</SPAN>C<SPAN 
lang=ZH-CN 
style="FONT-FAMILY: SimSun; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">域来表示一个更大范围的取值，可以来通知多处理器硬件在访问与其他处理器共享的页面数据时遵循何种协议。不具备硬件上的快存一致性协议特征的</SPAN>64<SPAN 
lang=ZH-CN 
style="FONT-FAMILY: SimSun; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">位</SPAN>CPU<SPAN 
lang=ZH-CN 
style="FONT-FAMILY: SimSun; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">保留了这样的</SPAN>TLB<SPAN 
lang=ZH-CN 
style="FONT-FAMILY: SimSun; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">入口的格式；在所有</SPAN>R4000<SPAN 
lang=ZH-CN 
style="FONT-FAMILY: SimSun; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">类型