[sprdlinux] some info about likely/unlikely

  • From: Orson Zhai <orsonzhai@xxxxxxxxx>
  • To: Chunyan Zhang <chunyan.zhang@xxxxxxxxxxxxxx>
  • Date: Sat, 20 Dec 2014 01:20:36 +0800


前几天你提到Greg K.H. 不推荐使用likely/unlikely,我看到这篇文章佐证了他 的观点

http://bitsup.blogspot.sg/2008/04/linux-kernel-likely-not-measured.html (需翻墙)

作者失望的发现,likely/unlikely没有带来任何实质的好处。通过这2个宏达到性 能优化,完全是程序员yy而已。

在Linux Newbie的FAQ结论里也提到,

> You should use it only in cases when the likeliest branch is very very very likely, or when the unlikeliest branch is very very very unlikely.

作者连用了3个very来表达其强烈的感情....

http://kernelnewbies.org/FAQ/LikelyUnlikely

P.S.

Grep K.H.除了是社区的2号人物外,也是LDD3的作者之一。



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