Stream使用教程

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.

 

[root@RedHat stream]# make

gcc -O2 stream.c -o stream

[root@RedHat stream]# ls

Makefile  stream  stream.c  stream.f

[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.

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Printing one line per active thread....

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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.

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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]#