多线程的内存注意事项 [英] Memory considerations with multithreading
问题描述
我正在C/C ++上实现am算法来处理一些矢量，我认为将其并行是一个好主意，因为我正在使用多核CPU.我有一些使用GPGPU的经验，不良的内存访问会破坏整个性能，我是否还需要考虑CPU内核之间的任何特殊访问布局?
I'm implementing am algorithm on C/C++ to process some vectors and I thought it could be a good idea to make it parallel since I'm working with a multicore CPU. I have some experience with GPGPU and there bad memory access can ruin the entire performance, do I need to consider any special access layout between the cores on the CPU also?
谢谢
推荐答案
使用多处理器设置可能会遇到许多与内存相关的问题，其中一些问题会使应用程序的爬网速度变慢.
There are a number of memory-related problems you can run into with a multiprocessor setup, and some of them can slow an application to a crawl.
您需要大致了解盒子上的缓存行大小，然后尝试2种操作:
You need to be roughly aware of the cache line size on your box and attempt 2 things:
- 限制单个线程按关闭时间顺序访问的数据高速缓存行(尤其是您写入的高速缓存行)的数量.即，避免不必要地弄脏"更多的缓存行.
- 避免像瘟疫那样，有两个单独的线程同时"通过一次写入来访问同一数据高速缓存行.
(如果要处理必须分页的大型数据结构，则以上两个规则也适用于数据页.)
(The above two rules also apply to data pages, if you're dealing with large data structures that must be paged.)
在可能的情况下，为每个线程设置单独的工作数据结构(尤其是堆)，而不是共享数据.特别要提防所有线程都会更新一个公共计数器，并且(显然)避免使用锁和信号灯，除非在关键时刻绝对需要同步线程.
Where possible, set up separate working data structures (especially heap) for each thread, rather than sharing the data. Especially beware of having a common counter that all threads update, and (obviously) avoid locks and semaphores except at critical junctures where you absolutely need to synchronize threads.
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