prefetching数据缓存为X86-64 [英] Prefetching data to cache for x86-64

问题描述

在我的应用程序，在一个点上，我需要内存中的数据（MBS 100年代）的一个大的连续的块上进行计算。我在想什么是保持prefetching我的计划将在未来的触摸，所以，当我在该部分执行计算，该数据已经在缓存中的块的一部分。

In my application, at one point I need to perform calculations on a large contiguous block of memory data (100s of MBs). What I was thinking was to keep prefetching the part of the block my program will touch in future, so that when I perform calculations on that portion, the data is already in the cache.

有人可以给我如何用gcc来实现一个简单的例子？我读 _mm_ prefetch 地方，但不知道如何正确使用它。另外请注意，我有一个多核系统，但每个核心将并行工作内存的不同区域。

Can someone give me a simple example of how to achieve this with gcc? I read _mm_prefetch somewhere, but don't know how to properly use it. Also note that I have a multicore system, but each core will be working on a different region of memory in parallel.

推荐答案

GCC 使用内建函数作为低级指令的接口。特别是对于你的情况<一个href=\"http://gcc.gnu.org/onlinedocs/gcc-4.7.0/gcc/Other-Builtins.html#Other-Builtins\"><$c$c>__builtin_$p$pfetch.但是，你在访问模式是不容易自动predict情况下使用这种时候只有应该看到一个可测量的差异。

gcc uses builtin functions as an interface for lowlevel instructions. In particular for your case __builtin_prefetch. But you only should see a measurable difference when using this in cases where the access pattern is not easy to predict automatically.

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