Linux：性能分析域

• 参考
• 工具
• • perf
  • BPF
• 域
• • 高速缓存相关
  • 编译器相关
  • • 数组与指针
    • inline 函数

【1】深入理解计算机系统

【1】如果程序，同时访问多个数组，而且发生冲突不命中的情况时，性能损耗比例是：L1与L2的访问时间比。冲突不命中的场景是：多个数组映射到了相同的高速缓存位置。这样导致高速缓存来回切换内容。

但是如果循环处理时，还是有性能的区别（在这本书中有详细的解释Computer architecture and design the hardware and software interface，是MIPS平台）：
The first program uses the expression (array[index] != 0). This requires the compiler to generate an index operation, which takes longer than a simple pointer de-reference: ((*array_ptr) != 0). The expression at the end of this program, array_ptr - array, computes how far array_ptr is into the array.

The most common high-level transformation is probably procedure inlining, which replaces a call to a function by the body of the function, substituting the caller’s arguments for the procedure’s parameters.
The downside of the inlining optimization is that the compiled code would be bigger if the inlined procedure is called from several locations. Such a code expansion might turn into lower performance if it increased the cache miss rate;
缺点是如果增加了缓存脱靶几率，会降低性能。