Parallel computing
并行計算
Parallel computing is a type of computation in which many calculations or the execution of processes are carried out simultaneously. Large problems can often be divided into smaller ones, which can then be solved at the same time. There are several different forms of parallel computing: bit-level, instruction-level, data, and task parallelism. Parallelism has been employed for many years, mainly in high-performance computing, but interest in it has grown lately due to the physical constraints preventing frequency scaling. As power consumption (and consequently heat generation) by computers has become a concern in recent years, parallel computing has become the dominant paradigm in computer architecture, mainly in the form of multi-core processors.
Dennard scaling
Dennard scaling, also known as MOSFET scaling, is a scaling law based on a 1974 paper co-authored by Robert H. Dennard, after whom it is named. Originally formulated for MOSFETs, it states, roughly, that as transistors get smaller their power density stays constant, so that the power use stays in proportion with area: both voltage and current scale (downward) with length.
Dennard在1974發(fā)了篇論文蹂安，預(yù)測說晶體管尺寸變小，功耗會同比變小，換句話說相同面積下功耗不變腻菇。
根據(jù)Moore’s Law蛋逾，晶體管數(shù)隨尺寸縮小按接近平方關(guān)系增長，和Dennard scaling放在一起就是說單位面積晶體管數(shù)不斷增加而功耗保持不變。過去他們一對好基友一起統(tǒng)治了近30年桶良，芯片性能隨工藝穩(wěn)定提升洞翩，芯片產(chǎn)業(yè)一片繁榮昌盛稽犁；不幸的是，到2005年為止骚亿，Dennard scaling提前終結(jié)了已亥，還記得倒霉的奔4嗎？也就是說来屠，單位晶體管功耗改進速度比尺寸縮小速度慢虑椎，這下好了，步調(diào)不一致就扯到蛋了俱笛。單位面積功耗持續(xù)上升導(dǎo)致的一個問題就是Dark Silicon捆姜。
Dark silicon
In electronics industry, dark silicon is the amount of circuitry of an integrated circuit that cannot be powered-on at the nominal operating voltage for a given thermal design power (TDP) constraint. This is a challenge in the era of nanometer semiconductor nodes, where transistor scaling and voltage scaling are no longer in line with each other, resulting in the failure of Dennard scaling. This discontinuation of Dennard scaling has led to sharp increases in power densities that hamper powering-on all the transistors simultaneously at the nominal voltage, while keeping the chip temperature in the safe operating range. According to recent studies, researchers from different groups have projected that, at 8 nm technology nodes, the amount of Dark Silicon may reach up to 50%-80% depending upon the processor architecture, cooling technology, and application workloads. Dark Silicon may be unavoidable even in server workloads with abundance of inherent client request-level parallelism.
現(xiàn)在處理器設(shè)計中的十分普遍的現(xiàn)象——dark silicon，也叫“暗硅”迎膜。意思是說泥技，由于功耗的限制，一個很高端的處理器磕仅，比如多核的珊豹，其實同一時刻只能有很少的一部分門電路能夠工作，其余的大部分處于不工作的狀態(tài)榕订，這部分不工作的門電路店茶，就叫做“暗硅”。
Kotlin
Google 官方推薦的 Andriod 開發(fā)語言
Kotlin is a statically-typed programming language that runs on the Java Virtual Machine and also can be compiled to JavaScript source code or uses the LLVM compiler infrastructure. Its primary development is from a team of JetBrains programmers based in Saint Petersburg, Russia (the name comes from Kotlin Island, near St. Petersburg). While the syntax is not compatible with Java, Kotlin is designed to interoperate with Java code and is reliant on Java code from the existing Java Class Library, such as the collections framework. Kotlin is similar to Apple's Swift.
Amdahl's law
In computer architecture, Amdahl's law (or Amdahl's argument) is a formula which gives the theoretical speedup in latency of the execution of a task at fixed workload that can be expected of a system whose resources are improved. It is named after computer scientist Gene Amdahl, and was presented at the AFIPS Spring Joint Computer Conference in 1967.
G.M.Amdahl在1967年提出了Amdahl’s law劫恒，針對并行處理的scalability給出了一個模型贩幻，指出使用并行處理的提速由問題的可并行的部分所決定。這個模型為并行計算系統(tǒng)的設(shè)計者提供了指導(dǎo)兼贸。
