計算機專業英語時文[Multicore Processors]
計算機專業英語時文[Multicore Processors]
Multicore Processors
In 1965, when he first set out what we now call Moore’s Law, Gordon Moore (who later co-founded Intel Corp.) said the number of components that could be packed onto an integrated circuit would double every year or so (later amended to 18 months).
In 1971, Intel’s 4004 CPU had 2,300 transistors. In 1982, the 80286 debuted with 134,000 transistors. Now, run-of-the-mill CPUs count upward of 200 million transistors, and Intel is scheduled to release a processor with 1.7 billion transistors for later this year.
For years, such progress in CPUs was clearly predictable: Successive generations of semiconductor technology gave us bigger, more powerful processors on ever-thinner silicon substrates operating at increasing clock speeds. These smaller, faster transistors use less electricity, too.
But there’s a catch. It turns out that as operating voltages get lower, a significant amount of electricity simply leaks away and ends up generating excessive heat, requiring much more attention to processor cooling and limiting the potential speed advance——think of this as a thermal barrier.
To break through that barrier, processor makers are adopting a new strategy, packing two or more complete, independent processor cores, or CPUs, onto a single chip. This multicore processor plugs directly into a single socket on the motherboard, and the operating system sees each of the execution cores as a discrete logical processor that is independently controllable. Having two separate CPUs allows each one to run somewhat slower, and thus cooler, and still improve overall throughput for the machine in most cases.
From one perspective, this is merely an extension of the design thinking that has for several years given us n-way servers using two or more standard CPUs; we’re simply making the packaging smaller and the integration more complete. In practice, however, this multicore strategy represents a major shift in processor architecture that will quickly pervade the computing industry. Having two CPUs on the same chip rather than plugged into two separate sockets greatly speeds communication between them and cuts waiting time.
The first multicore CPU from Intel is already on the market. By the end of 2006, Intel expects multicore processors to make up 40% of new desktops, 70% of mobile CPUs and a whopping 85% of all server processors that it ships. Intel has said that all of its future CPU designs will be multicore. Intel’s major competitors——including Advanced Micro Devices Inc., Sun Microsystems Inc. and IBM——each appear to be betting the farm on multicore processors.
Besides running cooler and faster, multicore processors are especially well suited to tasks that have operations that can be divided up into separate threads and run in parallel. On a dual-core CPU, software that can use multiple threads, such as database queries and graphics rendering, can run almost 100% faster than it can on a single-CPU chip.
However, many applications that process in a linear fashion, including communications, backup and some types of numerical computation, won’t benefit as much and might even run slower on a dual-core processor than on a faster single-core CPU.
多核心處理器
1965年，Gordon Moore首次提出了今天我們所說的摩爾定律。他(後來與人共同籌建了英特爾公司)說，能夠封裝進積體電路的元器件數目每年(後來修改成每十八個月)約翻一番。
1971年，英特爾的4004處理器有2300個電晶體。1982問世的80286有134000電晶體。今天，一般的處理器有高達2億隻電晶體，英特爾預定在今年晚些時候推出有17億隻電晶體的處理器。
多年來，處理器的這種進步是完全可以預測的: 一代接一代的半導體技術給我們帶來了在更薄的矽襯底上、工作在更高時鐘速度上的更大、更強的處理器。那些更小、更快的電晶體耗電也更少。
但總是有盡頭的。隨著工作電壓更低，漏電就更多，產生更多的熱量，就需要對處理器的冷卻給予更多的關注，這就限制了潛在的速度提高——可以把它當作熱障。
為了突破熱障，處理器生產廠家採用了一個新的策略，將兩個或更多完整的獨立處理器核心(即CPU)封裝在一個晶片上。這種多核心處理器能直接插入主機板的單個插座上，而作業系統把每個執行的核心看作一個分立的、可獨立控制的邏輯處理器。有了兩個獨立的CPU就允許每個CPU稍微執行得慢些，從而溫度就低一些，但在多數情況下，仍能改進機器整體的.吞吐量。
從某個角度看，這種多核心處理器只是已沿用多年的、採用兩個或更多標準CPU的多路伺服器設計思想的延伸，我們只是簡單地使之封裝得更小、整合更多的元器件。然而，在實踐中，多核心策略代表著處理器架構的重大轉變，將會在計算行業中快速流行。在同一晶片中有兩個CPU，而不是插入兩個分開的插座，極大地提高了CPU之間通訊的速度，降低了等待時間。
來自英特爾的第一個多核心CPU已經上市。英特爾希望到2006年底，多核心處理器在新銷售的桌上型電腦中達到40%、在移動CPU中達到70%、伺服器中達到85%。英特爾已經說過，將來所有的CPU設計都將是多核心的。英特爾的主要競爭對手，包括AMD、Sun和IBM，也都把寶押在了多核心處理器上。
多核心處理器除了執行溫度低、速度快，還非常適合那些操作可以分成不同執行緒以及並行執行的任務。在一個雙核心的CPU上，可以使用多執行緒的軟體(同時執行資料庫查詢和圖形生成)執行速度幾乎比單CPU晶片快了一倍。
但是，很多以線性方式處理的應用程式，如通訊、備份和某些型別的數值計算，在速度稍微慢一些的雙核心處理器上並不能比速度更快一些的單核心CPU上獲得更大的優勢。
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