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.

多內核處理器

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，能夠封裝進集成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個晶體管。1982問世的80286有134000晶體管。今天，一般的處理器有高達2億隻晶體管，英特爾預定在今年晚些時候推出有17億隻晶體管的處理器。

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硅襯底上、工作在更高時鐘速度上的更大、更強的處理器。那些更小、更快的晶體管耗電也更少。

但總是有盡頭的'。隨着工作電壓更低，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。

爲了突破熱障，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內核(即CPU)封裝在一個芯片上。這種多內核處理器能直接插入主板的單個插座上，而操作系統把每個執行的內核看作一個分立的、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稍微運行得慢些，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，這種多內核處理器只是已沿用多年的、採用兩個或更多標準CPU的多路服務器設計思想的延伸，我們只是簡單地使之封裝得更小、集成更多的元器件。然而，在實踐中，多內核策略代表着處理器架構的重大轉變，將會在計算行業中快速流行。在同一芯片中有兩個CPU，而不是插入兩個分開的插座，極大地提高了CPU之間通信的速度，降低了等待時間。

來自英特爾的第一個多內核CPU已經上市。英特爾希望到2006年底，多內核處理器在新銷售的臺式機中達到40%、在移動CPU中達到70%、服務器中達到85%。英特爾已經說過，將來所有的CPU設計都將是多內核的。英特爾的主要競爭對手，包括AMD、Sun和IBM，也都把寶押在了多內核處理器上。

多內核處理器除了運行溫度低、速度快，還非常適合那些操作可以分成不同線程以及並行運行的任務。在一個雙內核的CPU上，可以使用多線程的軟件(同時運行數據庫查詢和圖形生成)運行速度幾乎比單CPU芯片快了一倍。

但是，很多以線性方式處理的應用程序，如通信、備份和某些類型的數值計算，在速度稍微慢一些的雙內核處理器上並不能比速度更快一些的單內核CPU上獲得更大的優勢。