附：
记下查看cache信息的方法：
cat /sys/devices/system/cpu/cpu0/cache/index2/size
sudo dmidecode -t cache
还有一个链接http://igoro.com/archive/gallery-of-processor-cache-effects 上面的1、2、3、4示例在本地都做了测试，满有意思的。
本文内容如下：
在中心又跑了下指令集测试，顺便测试下在cache miss时write allocate和read allocate的区别。
当读时，无论对于write through 或 write back型cache，当发生cache miss时都会将数据调入cache
代码：
1 movl r0, #0x7000 2 movl r1, #0xaaaaaaaa 3 stw r1, [r0] 4 movl r1, #0xbbbbbbbb 5 stw r1, [r0]
ldw r1, [r0] 6 movl r0, #0x94007000 7 stw r1, [r0] 8 mytest: 9 stw, r1, [r0] 10 b mytest
对于unicore当使用write through(0x0c), 对应了read allocate
即：当对应数据不在cache中时，则在写的时候不会将数据不会调入cache
1 UNITY WRITE HADDR 00007000 Size 2 Data aaaaaaaa 2 UNITY WRITE HADDR 00007000 Size 2 Data bbbbbbbb 3 UNITY READ HADDR 00007000 Size 2 Data bbbbbbbb 4 UNITY READ HADDR 00007004 Size 2 Data xxxxxxxx 5 UNITY READ HADDR 00007008 Size 2 Data xxxxxxxx 6 UNITY READ HADDR 0000700c Size 2 Data xxxxxxxx 7 UNITY READ HADDR 00007010 Size 2 Data xxxxxxxx 8 UNITY READ HADDR 00007014 Size 2 Data xxxxxxxx 9 UNITY READ HADDR 00007018 Size 2 Data xxxxxxxx 10 UNITY READ HADDR 0000701c Size 2 Data xxxxxxxx
对于unicore当使用writeback(0x1c), 对应了write allocate
即：当对应数据不在cache时，则在写的时候会将数据调入cache
UNITY READ HADDR 00007000 Size 2 Data xxxxxxxx UNITY READ HADDR 00007004 Size 2 Data xxxxxxxx UNITY READ HADDR 00007008 Size 2 Data xxxxxxxx UNITY READ HADDR 0000700c Size 2 Data xxxxxxxx UNITY READ HADDR 00007010 Size 2 Data xxxxxxxx UNITY READ HADDR 00007014 Size 2 Data xxxxxxxx UNITY READ HADDR 00007018 Size 2 Data xxxxxxxx UNITY READ HADDR 0000701c Size 2 Data xxxxxxxx UNITY WRITE HADDR 14007000 Size 2 Data bbbbbbbb
注意：对于writeback下的数据记录中出现14007000地址，这时unicore特有的现象，和体系结构有关（此处没有开mmu，因此不涉及地址转换）