Amdahl's Law 程序可能的加速比取决于可以被并行化的部分. 如果没有可以被并行化的部分,则P=0,speedup=1,no speedup. 如果全部可以被并行化,P=1,speedup is infinite(in thecory).可以获得无穷大的加速比. 如果50%可以被并行化,maxmum speedup = 2. 如果有N个处理器并行: 并行化可扩展极限For example  P=.50/.90/.99,如下表所示: speed up N P=.50 P=.90 P=.99…

Amdahl's law - Wikipedia https://en.wikipedia.org/wiki/Amdahl%27s_law 阿姆达尔定律(英语:Amdahl's law,Amdahl's argument),一个计算机科学界的经验法则,因吉恩·阿姆达尔而得名.它代表了处理器并行运算之后效率提升的能力. 并行计算中的加速比是用并行前的执行速度和并行后的执行速度之比来表示的,它表示了在并行化之后的效率提升情况. 阿姆达尔定律是固定负载(计算总量不变时)时的量化标准.可用公式: 来表示…

首先给出阿姆达尔定律的数学公式描述: S(N)=1(1−p)+pN p:程序中可并行部分的程序在单核上执行时间的占比: N:处理器的数目(总的核心数) S(N):程序在 N 个处理器(总核心数)相对在单个处理器(单核)中的速度提升比: 当 p=0.8(可并行部分所占比较高),令 N→∞ ,此时 S(N)→5(因采用多核对速度提升的上限), 当 p=0.2(可并行部分所占比较低),令 N→∞,此时的 S(N)→1.25(因采用多核对速度提升的上限) 阿姆达尔定律表明,即使到了多核时代,并发程序的开…

The hardware we rely on is changing rapidly as ever-faster chips are replaced by ever-increasing numbers of cores. As a result, concurrency and parallelism, niche features today, will soon be a basic requirement for most software. Application develop…

谈完并行执行的原理,咱们再来谈谈优化,到底并行执行能给我们带来哪些好处,我们又应该注意什么呢,下面展开. Amdahl’s  Law 再谈并行优化前我想有必要谈谈阿姆达尔定律,可惜老爷子去年已经驾鹤先去了.…

https://en.wikipedia.org/wiki/Symmetric_multiprocessor_system A symmetric multiprocessor system (SMP) is a multiprocessor system with centralized shared memory called main memory (MM) operating under a single operating system with two or more homogen…

At this point, we’ve sent draw calls down from our app all the way through various driver layers and the command processor; now, finally we’re actually going to do some graphics processing on it! In this part, I’ll look at the vertex pipeline. But be…

https://en.wikipedia.org/wiki/Amdah's_law Amdahl's law is often used in parallel computing to predict the theoretical speedup when using multiple processors. For example, if a program needs 20 hours using a single processor core, and a particular par…

0.1 TopicNotes of Lin C., Snyder L.. Principles of Parallel Programming. Beijing: China Machine Press. 2008. (1) Parallel Computer Architecture - done 2015/5/24(2) Parallel Abstraction - done 2015/5/28(3) Scable Algorithm Techniques - done 2015/5/30(…

http://queue.acm.org/detail.cfm?id=1854041 The July/August issue of acmqueue is out now acmqueue is free for ACM professional members. Non-members can purchase an annual subscription for $19.99 or a single issue for $6.99. Download the app from iTune…