Stream使用教程

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#Stream #内存带宽测试

于 2013-07-28 22:33:48 首次发布

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本文详细介绍了如何使用Streambenchmark进行内存带宽和内核向量计算速度的基准测试，包括安装步骤、测试过程及结果解读。通过四个不同测试项（copy、scale、add、triad）的比较，展示了程序性能受内存带宽限制的现象。

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现在，计算机CPU运行速度的快速发展已经远远超过了内存的访问速度。越来越多的程序性能被内存带宽所限制，而不是计算机的CPU运行速率。

Stream benchmark是一个简单的合成基准测试程序，衡量内存带宽（MB /秒）和相应的内核向量的计算速度。

Each of the four tests adds independent information to the results:

1. “copy”：在没有算术的衡量传输速率；

2. “Scale”

``Copy'' measures transfer rates in the absence of arithmetic.
``Scale'' adds a simple arithmetic operation.
``Sum'' adds a third operand to allow multiple load/store ports on vector machines to be tested.
``Triad'' allows chained/overlapped/fused multiply/add operations.

1. 安装

[root@RedHat stream]# make
gcc -O2 stream.c -o stream
[root@RedHat stream]# ls
Makefile  stream  stream.c  stream.f

2. 测试

[root@RedHat stream]# ./stream
-------------------------------------------------------------
STREAM version $Revision: 5.9 $
-------------------------------------------------------------
This system uses 8 bytes per DOUBLE PRECISION word.
-------------------------------------------------------------
Array size = 2000000, Offset = 0
Total memory required = 45.8 MB.
Each test is run 10 times, but only
the *best* time for each is used.
-------------------------------------------------------------
Printing one line per active thread....
-------------------------------------------------------------
Your clock granularity/precision appears to be 6 microseconds.
Each test below will take on the order of 17340 microseconds.
   (= 2890 clock ticks)
Increase the size of the arrays if this shows that
you are not getting at least 20 clock ticks per test.
-------------------------------------------------------------
WARNING -- The above is only a rough guideline.
For best results, please be sure you know the
precision of your system timer.
-------------------------------------------------------------
Function      Rate (MB/s)   Avg time     Min time     Max time
Copy:        2264.0171       0.0154       0.0141       0.0169
Scale:       2212.8422       0.0154       0.0145       0.0164
Add:         2936.3309       0.0196       0.0163       0.0214
Triad:       2673.8123       0.0199       0.0180       0.0216
-------------------------------------------------------------
Solution Validates
-------------------------------------------------------------
[root@RedHat stream]#